• Journal of Biosystems Engineering
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• v.34 no.4
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• pp.211-219
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• 2009

In the process of oyster mushroom production, loading work of culture medium needs the most intensive labor power and cost. Therefore, the development of culture medium loading machine causes to reduce the manpower and cost. The main objectives of this study are identify cultivating environment, physical properties of culture medium and to make an element design of culture medium loading machine. The results are summarized as follows: 1. The moisture content and density of popularly used culture medium were 70%(w.b), $26\;kg/m^3$, respectively. 2. Pressure of the blower increased as the impeller speed increased, and the opening ratio of pressure controller decreased. 3. Recommendable c1earance(${\delta}$) between an impeller plate and a blower case was 25 mm at an impeller speed of 3183 rpm 4. Discharge device of type B with a hopper and suit was better than type A with a hopper.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.109-112
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• 1997

The Hydrodynamic performance of the trileaflet polymer prosthetic valves depends on the design of the leaflet and the physical properties of the leaflet membrane. In order to study the effect of leaflet membrane elasticity on the hemodynamic performance of trileaflet prosthetic valve, leaflet membranes are manufactured using two different polymers - Biospan and Tecoflex SG-93A. The hemodynamic performance parameters are measured under steady and physiological pulsatile flow, and compared with monoleaflet polymer valve(floating valve) and bileaflet mechanical valve(St. Jude Medical valve). Well designed trileaflet valve shows the lowest mean pressure drop among the tested valves. The trileaflet valves with Biospan membrane show lower pressure drop and back low comparing to those with Tecoflex membrane. More elastic membrane may provide wide opening area during systole and close membrane ree edge contact during diastole. Durability of trileaflet valves are also tested in vitro. Trileaflet valves with non-uniform membrane thickness ail within 17 days because of stress concentration. Trileaflet polymer valves with uniform membrane thickness perform well over 55 days without failure.

• The Korean Journal of Pain
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• v.12 no.1
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• pp.152-156
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• 1999

Spontaneous intracranial hypotension (SIH) is a rare syndrome which causes postural headache associated with low cerebrospinal fluid (CSF) pressure, without preceding events such as lumbar puncture, back trauma, operative procedure or illness. The headche is usually accompanied by nausea, vomiting, tinnitus, neck stiffness, vertigo, photophobia and in rare cases diplopia, transient visual obscuration. Brain MRI may show subdural effusion, downward displacement of brain and diffuse and continuous meningeal enhancement when enhanced by gadolinium. Low opening pressure was shown through lumbar puncture. The value of protein and cell count of CSF may be slightly elevated. This syndrome usually resolves itself spontaneously or with strict bed rest. When the headache is persistent or incapacitating, more aggressive treatment may be necessary. We treated two cases of SIH in which epidural blood patch produced immediate and complete relief of the symptoms.

• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1280-1290
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• 2016

This paper presents an advanced estimation method for obtaining the probability density functions of a damage parameter for valve leakage detection in a reciprocating pump. The estimation method is based on a comparison of model data which are simulated by using a mathematical model, and experimental data which are measured on the inside and outside of the reciprocating pump in operation. The mathematical model, which is simplified and extended on the basis of previous models, describes not only the normal state of the pump, but also its abnormal state caused by valve leakage. The pressure in the cylinder is expressed as a function of the crankshaft angle, and an additional volume flow rate due to the valve leakage is quantified by a damage parameter in the mathematical model. The change in the cylinder pressure profiles due to the suction valve leakage is noticeable in the compression and expansion modes of the pump. The damage parameter value over 300 cycles is calculated in two ways, considering advance or delay in the opening and closing angles of the discharge valves. The probability density functions of the damage parameter are compared for diagnosis and prognosis on the basis of the probabilistic features of valve leakage.

• Proceedings of the KWS Conference
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• 2001.05a
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• pp.220-223
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• 2001

In this study, CT specimens were prepared hem ASTM SA516 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -l$0^{\circ}C$ and -l2$0^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ΔK$_{th}$ in the early stage of fatigue crack growth ( Region I ) and stress intensity factor range ΔK in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN - ΔK in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region H and the cryogenic-brittleness greatly affect a material with decreasing temperature.e.greatly affect a material with decreasing temperature.

• Journal of ILASS-Korea
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• v.23 no.2
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• pp.58-65
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• 2018

An analytic strategy to control the variable valve actuation applied to two intake valves (flow port intake valve and swirl port intake valve) was performed in this study. we considered the variation in phasing of intake valve profiles by using the Cam-in-Cam technology. The analytic model was implemented in the GT-Power simulation program and analyzed the result of regulated emissions such as, NOx and Soot, especially with IMEP characteristics. Namely, we meticulously investigated the sources of having effect on the amount of NOx and soot formation under the test conditions with retard timing of both flow port and swirl port intake valves for decreasing the opening duration by 35CAD. Also, we analyzed the effect of incylinder pressure and temperature with NOx variations and in-cylinder pressure and temperature on NOx variations and normalized turbulent intensity. Through this analysis, some useful results on the combustion and flow characteristics of the swirl port and flow port control of the intake valve were obtained by this study.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.326-331
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• 2001

In this study. CT specimens were prepared from ASME SA5l6 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ in the range of stress ratio of 0.1 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ΔKsub/th/ in the early stage of fatigue crack growth ( Region I) and stress intensity factor range ΔK in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da.dN -ΔK in RegionII, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Archives of Craniofacial Surgery
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• v.18 no.3
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• pp.186-190
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• 2017

We report a case of free flap deterioration which may have been induced by pressure gradient resulting from cranial defect overlying a ventriculoperitoneal shunt (VP shunt). The patient, male and aged 78, had a VP shunt operation for progressive hydrocephalus. Afterwards, the scalp skin flap surrounding the VP shunt collapsed and showed signs of necrosis, exposing part of the shunt catheter. After covering the defect with a radial forearm free flap, the free flap site showed signs of gradual sinking while the vascularity of the flap remained unimpaired. An agreement was reached to remove the shunt device and observe the patient for any neurological symptoms, and after the shunt was removed and the previous cranial opening filled with fibrin glue by Neurosurgery, we debrided the deteriorated flap and provided coverage with 2 large opposing rotational flaps. During 2 months' outpatient follow-up no neurological symptoms appeared, and the new scalp flap displayed slight depression but remained intact. The patient has declined from any further follow-up since.

• Journal of Hydrogen and New Energy
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• v.20 no.6
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• pp.464-470
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• 2009

In order to analysis the possibility of high expansion and performance without backfire in a hydrogenfueled engine using external mixture injection, combustion characteristics and performance enhancement were analyzed in terms of retarding valve timing and increasing the boosting pressure. As the results, it was found that thermal efficiency increased by retarding intake valve timing with the same level of supplied energy is over 6.6% by the effect of high expansion including effect of combustion enhancement due to supercharging. It was also shown that the achievement of high power (equal to that of a gasoline engine), low brake specific fuel consumption and low emission (NOx of less than 16 ppm) without backfire in a hydrogen-fueled engine is possible around a boosting pressure of 1.5 bar, intake valve opening time of TDC and $\Phi$=0.35 in fuel-air equivalence ratio.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1993.05a
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• pp.82-82
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• 1993

Tracheostomy was done to form temporary opening in the trachea, to remove secretion, to maintain ventilation and to protect against aspiration. In recent times, with the development of care methods such as low pressure cuff, endotracheal intubation is being combined with tracheostomy in the treatment of patients who are treated long period in the intensive care units and the duration from endotracheal intabation to tracheostomy is like to prolong. To determine the proper time of tracheostomy in the patient in the intensive care units, authors reviewed retrospectively the 96 patients who received the tracheostomy procedure among the 8776 patients who were admitted in the intensive care units of Asan medical center form March 1990 to March 1993, and analyzed the complications of tracheostomy, decannulation and the cause of decannulation failure according to disease, age indication of endotracheal intubation and duration of endotracheal intubation.