• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.1
• /
• pp.94-100
• /
• 2005

This paper presents the behaviors of transient and effective impulse impedances of a long ground rod associated with the current injection points. The laboratory test for the time domain performance of actual-sized model ground rod subjected to a lightning stroke current has been carried out The transient ground impedances of long ground rods under impulse currents were higher than the ground resistance. Both of the ground resistance and the effective impulse ground impedance decrease with increasing the length of the ground rods. Also, the effective impulse ground impedances are significantly increased in fast rise time ranges. The reduction of the ground resistance is decisive to improve the impulse impedance characteristics of grounding systems. When the test current is injected at the bottom of ground rod, the oscillating pulses with high frequency are included on the wave front of ground rod potential and the effective impulse impedances are higher than any other cases.

• Polymer(Korea)
• /
• v.38 no.5
• /
• pp.645-649
• /
• 2014

The causes of residual stress in an injection molded part are high temperature variation and shear stress during molding process. Chemical cracking test is one of the methods of measuring residual stress and cracks are developed according to the degree of residual stress. In this study, the relationship between chemical cracking and exerted stress have been investigated. Deformation jig was designed and used to give a stress through deformation in a specimen. Specimens were molded by a hot press using polycarbonate (PC) and annealed to remove residual stresses in the specimens. Specimens were fixed in the deformation jig and immersed into the solvent to create cracks in the specimens. Solvents were prepared by using tetrahydrofuran and methyl alcohol. As stress accordance with the deformation in the specimen increased, the frequency and density of cracks in the specimen also increased. The results of this study can be used for the measurement of residual stress quantitatively in an injection molded PC product using a chemical cracking method.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.37 no.10
• /
• pp.65-72
• /
• 2000

In this paper, we propose an efficient technique to minimize the input offset of a dynamic latch comparator. We analyzed offset due to charge injection mismatching and unwanted positive feedback during sampling phase. The last one was only considered in the previous works. Based on the analysis, we proposed a modified dynamic latch with initialization switch. The proposed circuit was simulated using 0.65${\mu}m$ CMOS process parameter with 5v supply. The simulation results showed that the input offset is less than 5mV ant 200MHz sampling frequency and the input offset is improved about 80% compared with previous work in $5k{\Omega}$ input resistance.

• Journal of Embryo Transfer
• /
• v.30 no.3
• /
• pp.225-228
• /
• 2015

Understanding the behavior of transgenes introduced into oocyte or embryos is essential for evaluating the methodologies for transgenic animal production. To date, many studies have reported the production of transgenic pig embryos with, however, low efficiency in environment of blastocyst production. The aim of present study was to determine the expression and duration of transgene transferred by intracytoplasmic sperm injection-mediated gene transfer (ICSI-MGT). Embryos obtained from the ICSI-MGT procedure were analysed for the expression of GFP and then for the transmission of the transgene. Briefly, fresh spermatozoa were bound to exogenous DNA after treatment by Triton X-100 and Lipofectin. When ICSI-MGT was performed using sperm heads with tails removed, the yield of blastocyst (25.3%), treated with Lipofectin (18.8%) and Triton X-100 (19.2%) were observed. Treatments of Lipofectin or Triton X-100 did not further improve the rates of blastocysts. Moreover, the apoptosis rates of embryos were obtained from the control and LIpofectin groups (8.7%, 9.7%, respectively), but were significantly higher in the Triton X-100 group (13.0%). Our results demonstrated that ICSI-MGT caused minimal damage to oocytes that could develop to full term. Moreover, the embryos derived by ICSI-MGT have shown prolonged exogenous DNA expression during preimplantation stage in vivo. However, more efforts will be required to improve the procedures of both sperm treatments cause of high frequency of mosaicisms.

• Safety and Health at Work
• /
• v.7 no.1
• /
• pp.72-77
• /
• 2016

Background: This study aimed to determine the prevalence and factors related to needle stick injuries (NSIs) and to assess related safety measures among a sample of Iranian nurses. Methods: In this cross-sectional study, a random sample of 168 registered active nurses was selected from different wards of one of the hospitals of Shiraz University of Medical Sciences (SUMS). Data were collected by an anonymous questionnaire and a checklist based observational method among the 168 registered active nurses. Results: The prevalence of NSIs in the total of work experience and the last year was 76% and 54%, respectively. Hollow-bore needles were the most common devices involved in the injuries (85.5%). The majority of NSIs occurred in the morning shift (57.8%) and the most common activity leading to NSIs was recapping needles (41.4%). The rate of underreporting NSIs was 60.2% and the major reasons for not reporting the NSIs were heavy clinical schedule (46.7%) and perception of low risk of infection (37.7%). A statistically significant relationship was found between the occurrence of NSIs and sex, hours worked/week, and frequency of shifts/month. Conclusion: The study showed a high prevalence of NSIs among nurses. Supportive measures such as improving injection practices, modification of working schedule, planning training programs targeted at using personal protective equipment, and providing an adequate number of safety facilities such as puncture resistant disposal containers and engineered safe devices are essential for the effective prevention of NSI incidents among the studied nurses.

• Journal of Power Electronics
• /
• v.19 no.5
• /
• pp.1224-1234
• /
• 2019

Hybrid rotor position estimation methods that integrate a fundamental model and high frequency (HF) signal injection are widely used for the wide speed-range sensorless control of interior permanent-magnet synchronous machines (IPMSMs). However, the direct transition of two different schemes may lead to system fluctuations or system instability since two estimated rotor positions based on two different schemes are always unequal due to the effects of parameter variations, system delays and inverter nonlinearities. In order to avoid these problems, a seamless transition strategy to define and construct a virtual q-axis inductance is proposed in this paper. With the proposed seamless transition strategy, an estimated rotor position based on a fundamental model is forced to track that based on HF signal injection before the transition by adjusting the constructed virtual q-axis inductance. Meanwhile, considering that the virtual q-axis inductance changes with rotor position estimation errors, a new observer with a two-phase phase-locked loop (TP-PLL) is developed to accurately obtain the virtual q-axis inductance online. Furthermore, IPMSM sensorless control with maximum torque per ampere (MTPA) operations can be tracked automatically by selecting the proper virtual q-axis inductance. Finally, experimental results obtained from an IPMSM demonstrate the feasibility of the proposed seamless transition strategy.

• The Korean Journal of Physiology
• /
• v.19 no.2
• /
• pp.227-232
• /
• 1985

Previously, we had reported that the electrical stimulation of peripheral nerve with stimlatory parameters of 20 V strength and 2 Hz frequency for 60 min resulted in reducing the pain reaction. The present study was performed to evaluate if the pain reaction was affected by the peripheral nerve stimulation with different stimulatory parameters in the decerebrated cat. The flexion reflex was used as an index of the pain reaction. The reflex was elicited by stimulating the sural nerve (stimulus strength of 20 $V\;\times\;0.5$msec) and recorded as a compound action potential from the motor nerve innervated to the posterior biceps femoris muscle. The common perneal nerve was selected as a peripheral nerve on which the electrical stimulation of various intensities and frequencies was applied. The results are summarized as follows : 1) The peripheral nerve stimulation with 100 mV strength, regardless of frequencies, did not affect the pain reaction induced by the sural nerve stimulation. 2) When the stimulus of 1V intensity and slow frequency (2 Hz) was applied to the peripheral nerve for 30 min or 60 min, the pain reaction was significantly reduced comparing to the control. However, this reduced pain reaction by the peripheral nerve stimulation was not reversed by the injection of naloxone (0.02 mg/kg) 3) High frequency stimulus (60 Hz) of 1V intensity for 30 or 60 min did not show any effects of affecting the pain reaction. These results suggest that the stimulus of relatively high intensity (at least 1V) and low frequency (2 Hz) is needed to elicite the analgesic effect by the peripheral nerve stimulation. By the 1V stimulus, $A\delta$ nerve fiber is activated. Therefore, an $A\delta$ or smaller nerve fibers must be activated for showing analgesia by the peripheral nerve stimulation. However, the mechanism of analgesia by the $A\delta$ nerve activation alone was not related to the endogeneous morphine system since the reduced pain reaction by the $A\delta$ fiber activation alone was not reversed by the treatment of naloxone.

• Journal of Acupuncture Research
• /
• v.24 no.2
• /
• pp.211-220
• /
• 2007

Objectives : This study was to investigate the effect of high frequency electroacupuncture at $ST_{36}$ acupuncture point on the Complete Freund's Adjuvant (CFA) induced rat arthritis pain model. Methods : Arthritis was induced by intradermal injection of CFA into base of tail. Experimental groups were divided into 4 groups; Normal, Control and Jok-Samri ($ST_{36}$) and Non-Acupuncture point (NA). Normal group, non-arthritic group, was injected with normal saline，and the others groups were injected CFA. $ST_{36}$ group was treated by 120 Hz electroacupuncture at $ST_{36}$ acupuncture point, and NA group was treated by 120 Hz electroacupuncture at non-acupuncture point. Each groups were evaluated by the change of c-fos positive neurons in periaqueductal gray (PAG) and hippocampus by using an image analyzer and a microscope. Results: - In the PAG region, the number of fos-positive cells in the $ST_{36}$ group ($42.37{\pm}5.08$) were significantly (p<0.05) decreased compared with the control group ($64.56{\pm}6.35$). - In the PAG region, the number of fos-positive cells in the NA group were meaninglessly decreased compared with the control group - In the Cornu Ammonis(CA)l region of hippocampus, the number of fos-positive cells in the $ST_{36}$ group ($7.00{\pm}1.08$) and NA group ($5.56{\pm}2.01$) were significantly (p<0.05) decreased compared with the control group ($13.81{\pm}1.24$). - In the dentate gyrus region of hippocampus, the number of fos- positive cells in the $ST_{36}$ group ($10.75{\pm}0.98$) and NA group ($6.56{\pm}0.78$) were significantly (p$26.45{\pm}1.82$). Conclusions : It is expected that high frequency electroacupuncture can be used a treatment of arthritic pain.

• The Journal of Engineering Geology
• /
• v.20 no.4
• /
• pp.425-436
• /
• 2010

We established a stochastic 3-D fracture network system for fractured rock masses located in Il-Gwang Mine, Busan, to explore the relationship between the acidity of mine drainage and fracture geometry. A field scanline survey and borehole image processing were performed to estimate the best probability distributions of fracture geometry parameters. The stochastic 3-D fracture network system constructed for the rock masses was validated and deemed to be successful. The 3-D fracture network model was suitable for developing conceptual ideas on fluid flow in fractures at a field experimental site. An injection well and three observation wells were drilled at the field experimental site to monitor the acidity of mine drainage induced by the injection of fresh water. The field experiment, which was run for 29 days, yielded a significant relationship (with a high coefficient of determination) between the fracture geometry parameters and the acidity of mine drainage. The results show that pH increased with increasing relative frequency of fracture strike, and decreased with increasing fracture density. The concentration of $SO^{2-}_4$ decreased with increasing relative frequency of fracture strike, and increased with increasing fracture density.

• The Korean Journal of Physiology
• /
• v.22 no.2
• /
• pp.231-243
• /
• 1988

This study was performed to investigate the mechanism of changes in arterial blood pressure, as a typical example of somatosympathetic reflex, induced by activation of muscular afferent nerves. Cats were anesthetized with ${\alpha}-chloraloae$ (60 mg/kg, i.p.). Afferent fibers in muscle nerve were activated by various method muscle contraction, electrical stimulation of muscle nerves, intraarterial injection of some algesic substances and noxious mechanical stimulation etc-and the evoked changes in arterial blood pressure were monitored. The effects of intravenous or direct spinal administration of morphine on the changes in arterial blood pressure induced by activation of the muscle afferent fibers were observed and also the effects of spinal lesions made in the $L1{\sim}L3$ spinal cord on them were studied to identify the ascending spinal pathways of the somatosympathetic reflexes. Followings are the results obtained. 1) The stimulation of medial gastrocnemius nerve under non-paralyzed condition with C-strength, low frequency (lower than 20 Hz) stimuli elicited a depressor response and a pressor response was elicited with C-strength, high frequency stimuli, of which the maximal response was observed at 100 Hz stimulation. 2) When the animal was paralyzed, depressor response to stimulation of the medial gastrocnemius nerve was observed with C-strength, $0.5{\sim}5Hz$ stimuli although the amplitude of the depressor response was decreased. The maximal pressor response was observed during stimulation with C-strength, $20{\sim}100Hz$ stimuli. 3) Intraarterial injection of some algesic substances induced marked pressor responses while noxious mechanical stimulation of the medial gastrocnemius muscle was not enough to elicit any significant changes (larger than 10 mmHg) in arterial blood pressure. 4) Systemically administered morphine (2 mg/kg) lowered the arterial blood pressure immediately and persistently and it was reversed by administration of naloxone. Direct spinally administered morphine did not elicit any changes. 5) The pressor response elicited by the activation of muscle afferent nerves was strengthened by systemic morphine administration while the depressor response tended to decrease. 6) Morphine administered on the spinal cord directly, decreased pressor response but did not change depressor response. From the above results it is concluded that there are separate groups of afferent nerves in the medial gastrocnemius nerve, which elicit pressor and depressor responses and the spinal ascending pathways of them are also separated from each other.