• Journal of ILASS-Korea
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• v.8 no.2
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• pp.1-6
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• 2003

The liquid phase LPG injection (LPLI) system (the third generation technology) has been considered as one of the next generation fuel supply systems for LPG vehicles, since it has a very strong potential to accomplish the higher power, higher efficiency, and lower emission characteristics than the mixer type(the second generation technology) fuel supply system However. when a liquid LPG fuel is injected into the inlet duct of an engine, a large quantity of heat is extracted due to evaporation of fuel. This leads to freezing of the moisture in the air around the outlet of a nozzle, which is called icing phenomenon. It may cause damage to the outlet nozzle of an injector or inlet valve seat. In this work, the experimental investigation of the icing phenomenon was carried out The results showed that the icing phenomenon and process were mainly affected by humidity of inlet air instead of air temperature in the inlet duel. Also, it was observed that the total ice formed around the nozzle weighs at about $150mg{\sim}260mg$ after injection for ten minutes. And some fuel species were found in the ice attached at the front side of a nozzle, while frozen ice attached at the back of a nozzle was mostly' consisted of moisture of inlet air. Therefore, some frozen ice deposit. detached from front nozzle of an injector, may cause a problem of unfavorable air fuel ratio control in the small LPLI engine.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.105-110
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• 2011

The doping procedure in crystalline silicon solar cell fabrication usually contains oxygen injection during drive-in process and removal of phosphorous silicate glass(PSG). In this paper, we studied the effect of oxygen injection and PSG on conversion efficiency of solar cell. The mono crystalline silicon wafers with $156{\times}156mm^2$, $200{\mu}m$, $0.5-3.0{\Omega}{\cdot}cm$ and p-type were used. After etching $7{\mu}m$ of the surface to form the pyramidal structure, the P(phosphorous) was injected into silicon wafer using diffusion furnace to make the emitter layer. After then, the silicon nitride was deposited by the PECVD with 80 nm thickness and 2.1 refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$880^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Solar cells with four different types were fabricated with/without oxygen injection and PSG removal. Solar cell that injected oxygen during the drive-in process and removed PSG after doping process showed the 17.9 % conversion efficiency which is best in this study. This solar cells showed $35.5mA/cm^2$ of the current density, 632 mV of the open circuit voltage and 79.5 % of the fill factor.

• The Korean Journal of Pain
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• v.18 no.1
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• pp.15-18
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• 2005

Background: Epidural steroid injections (ESI) have been used widely for the treatment of back and radiating extremity pain. Although its effects on the metabolic and endocrine system have been studied, the effects following repeated injections remain to be determined. We studied the effects of three repeated caudal epidural injections of low dose triamcinolone. Methods: the subject were 10 elderly women with spinal stenosis. Caudal epidural injections were performed biweekly. Triamcinolone (20 mg), mixed with 15 ml of 0.25% lidocaine, was used as the ESI injectate. The procedures were performed with the patient in the prone position. Blood sampling was performed just before the first injection, and used as the baseline, and then just before each injection on the same day of the 2nd and 4th weeks, with the last samples taken 2 weeks after the third injection. Results: The blood glucose concentrations showed no significant changes. The blood cortisol and ACTH concentrations were significantly decreased after the first injection, but there were no further decreases after each of the subsequent injections. The cortisol concentrations were maintained within the normal range. Conclusion: Caudal epidural injections, with low dose triamcinolone, suppressed the hypothalamus-pituitary-adrenal (HPA) axis, but no further suppression followed the subsequent repeated injections. Three consecutive caudal injections at 2 week intervals seems to be a safe procedure.

• The Journal of Engineering Geology
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• v.32 no.3
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• pp.389-399
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• 2022

Observations on the influence of the fluid infiltration on the breakdown pressure during laboratory hydraulic fracturing tests, along with an analysis of the applicability of the breakdown pressure prediction for cylindrical samples using Quasi-static and Linear Elastic Fracture Mechanics approaches were carried out. These approaches consider fluid infiltration through the so-called radius of fluid infiltration or crack radius, a parameter that is not a material property. Two sets of tests under pressurization rate controlled and injection rate controlled tests were used to evaluate the applicability of these methods. The difficulty of the estimation of the radius of fluid infiltration was solved by back calculating this parameter from an initial set of tests, and later, the obtained relationships were used to predict breakdown pressures for a second set of tests. The results showed better predictions for the injection rate than for the pressurization rate tests, with average errors of 3.4% and 18.6%, respectively. The larger error was attributed to differences in the testing conditions for the pressurization rate tests, which had different applied vertical pressures. On the other hand, for the tests carried out under constant injection rate, the Linear Elastic Fracture Mechanics solution reported lower errors compared to the Quasi-static solution, with values of 3% and 3.8%, respectively. Moreover, a sensitivity analysis illustrated the influence of the radius of fluid penetration or crack radius and the tensile strength on the breakdown pressure, suggesting a need for a careful estimation of these values. Then, the calculation of breakdown pressure considering fluid infiltration in cylindrical samples under triaxial conditions is possible, although larger data sets are desirable to validate and derive better relations.

• Journal of Society of Preventive Korean Medicine
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• v.22 no.3
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• pp.1-10
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• 2018

Backgrounds : In 2017, National Health Insurance implemented the pilot insuring project for Chuna manual therapy(CMT). 65 Korean Medicine(KM) hospitals and clinics were selected in the project to monitor the provision of insured CMT. Objectives : This study aimed to evaluate the effectiveness of CMT for low back pain provided in the real world setting. Methods : Patients with low back pain who agreed to participated in the study were enrolled and requested to complete questionnaires. Patients who received CMT regardless of receiving other KM therapies were classified to Chuna group, and patient who received KM therapies without CMT to KM group. Pain(pain-VAS) and back function(KODI, Oswestry disability index-Korean version), quality of life were assessed at baseline, 4 weeks, and 8 weeks. Additionally, patients who received CMT twice and more, and who's pain-VAS 20 and over were included, and patients who used pain injection were excluded in the analysis. Results : Of 371 patients who completed all questionnaire (mean age=42.6years, SD=12.45; 61% female), 96 were excluded, 170 were in Chuna group, and 105 were in KM group. Proportions of patients who had low back pain for more than twelve weeks in the Chuna group and KM group were 57.7% and 24.8%, respectively. Pain and back function were significantly improved on 4weeks and 8weeks in both groups, but there was no difference between two groups. For the patients in the sub-acute and chronic stage(>=12 weeks), change of total KODI scores in the Chuna group was higher than KM group(p=0.013) at 4weeks. Conclusions : CMT with other KM therapies can improve back function in the sub-acute and chronic patients. For insurance policy decision, economic evaluation of CMT is needed.

• Clinical and Experimental Reproductive Medicine
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• v.11 no.2
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• pp.17-25
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• 1984

Hypothalamic-pituitary function in patients of 6 selected groups of amenorrhea was evaluated by performing premarin test. Selected amenorrheic patients were divided into 6 groups of Turner's syndrome(5), adrenogenital syndrome(3), Sheehan's syndrome(4), moderate hyperprolactinemia(3), severe hyperprolactinemia(9) and functional oligoamenorrhea(9) the diagnoses of which were performed according to modified our own protocol for management of amenorrheic patients. As control 20 normally cycling women in mid follicular phase determined by their symptothermal charts during last 6 months designed by WHO were compared. The premarin test which is one of the tests evaluating the hypothalamic-pituitary function by the principle of negative and positive feed back effect's of estrogen was performed by injecting 20 mg of premarin in volus intravenously. The levels of serum LH before, 24, 48, 72, 96 and 120 hours after injection of premarin were measured by double antibody technique radioimmunoassay the reagents of which were supplied by WHO. The results were as follows: 1. Both negative and positive feed back effects by exogenous estrogen were well preserved even in the patients of gonadal dysgenesis although the baseline levels were much higher than normal. 2. In the patients of Sheehan's syndrome one could observe the minimal response of feed back effect in the case with minimal pituitary function. 3, Androgens in adrenogenital syndrome and prolactin in hyperprolactinemia may suppress mainly the positive feed back effect rather than the negative one. The suppressive effect can be abolished by proper treatments which can eliminate those suppressive hormones. 4. This premarin test may be beneficial for predicting the result of clomiphene in ovulation induction.

• The Journal of the Korea Contents Association
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• v.20 no.6
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• pp.439-444
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• 2020

The purpose of this study is to seek an alternative method to prevent the contamination of normal saline caused by the back-flow of Gadolinium Based Contrast Agent(GBCA) by the use of auto-injector for dynamic MRI. The research method is to manufacture the non-return valve as an alternative to the existing, and to examine the usefulness of the normal saline by dividing the state of normal saline into three groups. The signal intensity were compared. As a result, there was no statistically significant difference between normal saline before injection of group 1 and group 3 non-return valve (p> 0.05). It is analyzed that the self-produced non-return valve completely blocked the GBCA back to normal saline when the GBCA was injected. In conclusion, the application of the non-return valve presented in this study for dynamic MRI imaging using the auto injector can prevent normal saline contamination due to GBCA back-flow.

• The Korean Journal of Pain
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• v.13 no.1
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• pp.74-78
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• 2000

Background: Epidural Adhesiolysis is an interventional pain management technique for patients with low back pain. In addition to local anesthetics and corticosteroid, hypertonic saline (NaCl) are used for the technique. Present study was aimed to compare analgesic and adverse effects of two different concentration of hypertonic saline in Epidural Adhesiolysis. Methods: Fifty-three subjects with low back pain with radiculopathy were assigned to one of two epidural adhesiolysis treatment groups: 8% (Group I, n=26) or 10% (Group II, n=27) hypertonic saline. 17 G epidural needle was inserted at sacral hiatus and catheter was advanced untill its tip was located at lesion site under fluoroscopic guidance. Subjects in all treatment groups received epidural corticosteroid and local anesthetic. And then, hypertonic saline injection via catheter were carried out daily for 3 days. Evaluation included assessment of pain relief (Numerical Rating Scale; NRS) at post-epidural adhesiolysis 1, 2, 3 days, 1 week, and 1, 3 months. We also looked for complications of epidural adhesiolysis at different concentration of hypertonic saline. Results: Statistical analysis demonstrated that NRS was not significantly different between two groups during 3 months after epidural adhesiolysis. There were no major differences of complications between two groups and disappeard after a few months without residual sequelae. Conclusions: We conclude that epidural adhesiolysis using 8% hypertonic saline is effective for relief of low back pain with proven lumbosacral fibrosis without any residual sequelae compared with 10%.

• The Korean Journal of Pain
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• v.14 no.2
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• pp.218-224
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• 2001

Background: Response to diagnostic blocks does not consistently predict the outcome of interventional facet denervation. We investigated the relationship between pain relief by the percutaneous radiofrequency denervation of the lumbar zygapophysial joints with the result of facet joint diagnostic local anesthetic injection in patients with back pain originating from the lumbar zygapophysial joint. Methods: There were 35 patients enrolled, with ranging in age from 25 to 76 years ($52.6{\pm}12.7$ years, mean ${\pm}$ SD). We studied 7 men (20%) and 28 women (80%). All patients underwent double diagnostic block of $L_{3/4}$, $L_{4/5}$ and $L_5-S_1$ facet joint with 0.5% bupivacaine. The 35 patients fell into the following group. (1) Group A (n = 16): those who felt clear relief (pain free with Likert scale) from the double diagnostic block (2) Group B (n = 19): 11 patients who were always equivocal in their response to the double diagnostic block and 8 patients who were either pain free or equivocal in their response to the double diagnostic block. All 11 patients were done the facet joint denervation. The effect on the pain was evaluated with 4 point Likert scale 1, 6 and 12 weeks after the procedure. We evaluated the relationship between the pain response to diagnostic block and the pain relief with facet joint denervation. Results: Significant correlation was observed between the response to diagnostic block and pain relief with facet denervation (P < 0.05). We found no correlation between the categories of spinal operation and pain response to facet denervation (P value > 0.05). Conclusions: A satisfactory result of lumbar facet joint denervation can be obtained in many patients, especillay in patients whose pain were relieved by the diagnostic double facet joint block. It may be said that facet joint denervation for mechanical low back pain using radiofrequency thermocoagulation is a safe, easy, and repeatable technique.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1584-1590
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• 2017

This paper presents a implementation method of reliable speed limitation controller considering motor parameter variation in high speed operation. In spinning process of drum washing machine, speed increase has to be limited when unallowable imbalance mass is detected. Otherwise, severe noise and vibration can happen because noise and vibration are proportional to imbalance mass. To detect imbalance mass, d-axis current magnitude is used. However, we have to compensate for back-emf and power supply variation by means of detecting them because d-axis current is affected by both of them. On the other hand, we have to carefully estimate back-emf because back-emf is affected by stator resistance variation and inverter voltage error. Stator resistance variation can happen by manufacturing process for mass production or temperature variation in running. And there are inverter voltage errors between command voltage from micro-computer to inverter and real voltage from inverter to motor because of rising and falling time delay and turn-on resistance of power semiconductor switch. To solve this problem, we propose 2-step align current injection method which is to inject step-wise current right before starting. By this method, we can simply obtain stator resistance by ratio of voltage without inverter voltage error and current, and we can measure inverter voltage error. So we can obtain more exact model current, and then by simple calculation with compensation gain, we can estimate more accurate motor back-emf. We show that this method works well. It is verified through experiments.