• The Korean Journal of Pharmacology
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• v.22 no.2
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• pp.105-114
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• 1986

This study was undertaken to search for a new antiarrhythmic agent in natural plants. Extracts of Buxus microphylla var. koreana Nakai have been used as folk remedies of several diseases, including malaria and venereal disease, but any study on the pharmacological actions of this plant has not yet been carried out and its active ingredients have not been identified. In our laboratory, we isolated buxuletin (nonalkaloid) and cyclobuxine D (steroidal alkaloid) from Buxus microphylla var. koreana Nakai and reported their pharmacological actions: diuretic effects of buxuletin in rabbits and hypotensive effect of cyclobuxine D in rats. In the present study, we investigated the effect of cyclobuxine D on isolated frog heart and heart rate in urethane anesthetized rats. In order to clarify the mechanism of bradycardic effect of cyclobuxine D, we examined the changes of the ECG parameters (PR, QRS and R ${\alpha}$ T interval) produced by intravenous injection of cyclobuxine D in anesthetized rats. Cyclobuxine D depressed the contractile force in isolated frog heart and exerted a dose-dependent bradycardic effect in anesthetized rats. Intracerebroventricular injection of cyclobuxine D caused a fall in blood pressure and an increase in heart rate, but those effects were not significant. Cyclobuxine D prolonged the PR interval and RaT interval (${\alpha}$ Tindicates the apex of T), but was without significant effects on the duration of the QRS complex and PRc in urethane anesthetized rats.

• Clinical and Experimental Reproductive Medicine
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• v.43 no.4
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• pp.247-252
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• 2016

Objective: Heparin can modulate proteins, and influence processes involved in implantation and trophoblastic development. This study aimed to assess the improvement of clinical pregnancy and implantation rates after local intrauterine injection of low-molecular-weight heparin (LMWH) in patients undergoing intracytoplasmic sperm injection (ICSI). Methods: A randomised case/control design was followed in women scheduled for ICSI. The study arm was injected with intrauterine LMWH during mock embryo transfer immediately following the ovum pickup procedure, while the control arm was given an intrauterine injection with a similar volume of tissue culture media. Side effects, the clinical pregnancy rate, and the implantation rate were recorded. Results: The pregnancy rate was acceptable (33.9%) in the LMWH arm with no significant reported side effects, confirming the safety of the intervention. No statistically significant differences were found in the clinical pregnancy and implantation rates between both groups (p= 0.182 and p= 0.096, respectively). The odds ratio of being pregnant after intrauterine injection with LMWH compared to the control group was 0.572 (95% confidence interval [CI], 0.27-1.22), while the risk ratio was 0.717 (95% CI, 0.46-1.13; p= 0.146). No statistical significance was found between the two groups in other factors affecting implantation, such as day of transfer (p= 0.726), number of embryos transferred (p= 0.362), or embryo quality. Conclusion: Intrauterine injection of LMWH is a safe intervention, but the dose used in this study failed to improve the outcome of ICSI. Based on its safety, further research involving modification of the dosage and/or the timing of administration could result in improved ICSI success rates.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.5
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• pp.579-585
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• 2018

This study is to figure out the fuel injection characteristics according to the injection pressure and engine speed in the fuel supply system for gas fuel. The fuel rail pressure was from 1.5 to 6.0 bar by 1.5 bar increment and engine speed was set 1,000 ~ 6,000 RPM at interval of 1000 RPM. Considering the real engine operation, the injection pulse width was set 2.5ms, 5.0ms, and 13.0ms which correspond low, mid and high load condition respectively. In conclusion, in case of 100cc fuel rail, 4.5 bar of injection pressure showed best performance and the minimum required injection quantity 53cc which guarantees engine output can be obtained in each 1000~ 6000 rpm engine speed.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.25 no.2
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• pp.31-35
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• 2019

Kimchi is a refreshing sour food which gives sour and carbonic acid taste of carbon dioxide produced during the fermentation process. So, carbon dioxide injection was tried to raise carbonic acid taste of kimchi stored in the airtight container. First, carbon dioxide injection times of a given gas supply system were determined experimentally to attain initial concentration of 80% for different solid/liquid ratios. Since carbon dioxide is dissolved in kimchi to decrease its concentration during storage, periodical carbon dioxide injection conditions were needed and determined to keep the $CO_2$ concentration above 70%. For the initial flushing to 80% $CO_2$ concentration in model system filled with water, the injection time ranged from 40 to 89 seconds for free volumes of 2-8 L. $CO_2$ injection conditions for the under-ripened storage at $10^{\circ}C$ consisted of longer time at more frequent cycles for watery kimchi than for Chinese cabbage kimchi. At $0^{\circ}C$ of subsequent ripened stage storage of watery kimchi, the periodical injection at 3 hour interval was required because of continuous dissolution of carbon dioxide. However, Chinese cabbage kimchi did not require subsequent $CO_2$ injection during the ripened state storage and needed only flushing to 80% $CO_2$ at time of the container opening and closing. These results can be used as basic information for the programmed control of $CO_2$ injection in the kimchi container system.

• Design & Manufacturing
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• v.13 no.2
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• pp.17-21
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• 2019

In this study, selective laser sintered 3D printing mold core and metal core were used to investigate the difference of the thickness shrinkage from the gate of the injection molded part at a constant interval. SLS 3D printing mold core was made of nylon-based PA2200 powder and the metal core was manufactured by conventional machining method. As the PA2200 powder material has low strength, thermal conductivity and high specific heat characteristics compared with metal, molding conditions were set with the consideration of molten temperature and injection pressure. Crystalline resin(PP) and amorphous resin(PS) with low melting temperature and viscosity were selected for the injection molding experiment. Cooling time for processing condition was selected by checking the temperature change of the cores with a cavity temperature sensor. The cooling time of the 3D printing core was required a longer time than that of the metal core. The thickness shrinkage of the molded part compared to the core depth was measured from the gate by a constant interval. It was shown that the thickness shrinkage of the 3D printing core was 2.02 ~ 4.34% larger than that of metal core. In additions, in the case of metal core, thickness shrinkage was increased with distance from the gate, on the contrary, in the case of polymer core showed reversed aspect.

• The Korean Journal of Pain
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• v.27 no.1
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• pp.35-42
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• 2014

Background: Epidural steroid injection (ESI) is one of the most common procedures for patients presenting low back pain and radiculopathy. However, there is no clear consensus on what constitutes appropriate steroid use for ESIs. To investigate optimal steroid injection methods for ESIs, surveys were sent to all academic pain centers and selected private practices in Korea via e-mail. Methods: Among 173 pain centers which requested the public health insurance reimbursements for their ESIs and were enrolled in the Korean Pain Society, 122 completed questionnaires were returned, for a rate of 70.5%; also returned were surveys from 39 academic programs and 85 private practices with response rates of 83.0% and 65.9%, respectively. Results: More than half (55%) of Korean pain physicians used dexamethasone for ESIs. The minimum interval of subsequent ESIs at the academic institutions (3.1 weeks) and the private practices (2.1 weeks) were statistically different (P = 0.01). Conclusions: Although there was a wide range of variation, there were no significant differences between the academic institutions and the private practices in terms of the types and single doses of steroids for ESIs, the annual dose of steroids, or the limitations of doses in the event of diabetes, with the exception of the minimum interval before the subsequent ESI.

• Korean Journal of Radiology
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• v.25 no.3
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• pp.257-266
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• 2024

Objective: To investigate molecular and functional consequences of additional exposures to iodine- or gadolinium-based contrast agents within 24 hours from the initial intravenous administration of iodine-based contrast agents through an animal study. Materials and Methods: Fifty-six Sprague-Dawley male rats were equally divided into eight groups: negative control, positive control (PC) with single-dose administration of CT contrast agent, and additional administration of either CT or MR contrast agents 2, 4, or 24 hours from initial CT contrast agent injection. A 12 µL/g of iodinated contrast agent or a 0.47 µL/g of gadolinium-based contrast agent were injected into the tail vein. Serum levels of blood urea nitrogen, creatinine, cystatin C (Cys C), and malondialdehyde (MDA) were measured. mRNA and protein levels of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated. Results: Levels of serum creatinine (SCr) were significantly higher in repeated CT contrast agent injection groups than in PC (0.21 ± 0.02 mg/dL for PC; 0.40 ± 0.02, 0.34 ± 0.03, and 0.41 ± 0.10 mg/dL for 2-, 4-, and 24-hour interval groups, respectively; P < 0.001). There was no significant difference in the average Cys C and MDA levels between PC and repeated CT contrast agent injection groups (Cys C, P = 0.256-0.362; MDA, P > 0.99). Additional doses of MR contrast agent did not make significant changes compared to PC in SCr (P > 0.99), Cys C (P = 0.262), and MDA (P = 0.139-0.771) levels. mRNA and protein levels of KIM-1 and NGAL were not significantly different among additional CT or MR contrast agent groups (P > 0.05). Conclusion: A sufficient time interval, probably more than 24 hours, between repeated contrast-enhanced CT examinations may be necessary to avoid deterioration in renal function. However, conducting contrast-enhanced MRI on the same day as contrast-enhanced CT may not induce clinically significant kidney injury.

• Design & Manufacturing
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• v.7 no.1
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• pp.60-63
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• 2013

Recently, Silicone that one of the thermo-sets is used to making optical products such as LED lenses because of excellent thermal properties. LED lenses are required to keep the precise dimensions, so they must be molded to have the minimum deformation. Thermo-sets have the expansion characteristic on the part of thermal property, it is important to optimize the cure condition so that the deformation of the part become minimum. In this study, to investigate the relationship between the shrinkage by the curing and expansion by the thermal properties of the resin, reactive injection experiment was performed by setting the variables such as mold setting temperature, cure time. As a result, it was confirmed that there was a interval while the thermal properties were transferred to more active during the cure process. It is expected to help in determining the reactive injection molding conditions of the thermo-set parts as well as LED lens in order to reduce the amount of deformation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.378-381
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• 2009

A rotating stall, an instable phenomenon of compressor, brings about reducing the pressure rise, the efficiency of compressor and a mechanical demage. In order to improve instability and extend operating range, it was performed that a stability enhancement experiment applying air injection method at the 4-stage low-speed axial compressor. The coanda nozzle was used to inject air in axial direction at rotor tip and 8 injectors were set up at regular interval at the upstream of 1st stage rotor. At 80% speed, injectors were worked before rotating stall happened. As injecting the 5.4% air of mode inception flow rate, the stability of compressor operation enhanced about 4%.

• The Korean Journal of Pain
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• v.36 no.1
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• pp.106-112
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• 2023

Background: Most international bodies recommended against musculoskeletal steroid injection during the COVID-19 pandemic, fearing that the immunosuppressive effects of the steroid could worsen COVID-19 infection, thus prolonging the suffering of patients with severe musculoskeletal disease. The authors' aim is to analyze the risk of COVID-19 infection after musculoskeletal injections. Methods: This is a retrospective study of patients who visited a sports medicine clinic and received musculoskeletal steroid injections between January 1, 2020 and February 28, 2021. The collected data was compared with the national COVID-19 registry to identify positive COVID-19 patients. The patients were only considered positive for COVID-19 following corticosteroid injection within 3 months after injection. Results: Out of 502 steroid injections; 79.7% (n = 400) received a single injection in one day, 19.1% (n = 96) received steroid injections at 2 sites in one day, and 1.2% (n = 6) received steroid injections at 3 sites in one day. Using the Fisher's exact test, there was no statistically significant association of COVID-19 infection between the steroid group and control group (relative risk, 1.44; 95% confidence interval, 0.9-23.1, P = 0.654). Only one patient contracted mild COVID-19 with no post COVID complications. Conclusions: The authors recommend the use of musculoskeletal steroid injections in clinically indicated situation without having increased risk of COVID-19.