• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 연약지반처리위원회 학술세미나
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• pp.59-70
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• 2000

본 연구에서는 콘관입속도가 콘관입시험 결과에 미치는 영향을 연구하기 위하여 LSU/CALCHAS(Louisiana State University Calibration Chamber System)를 이용한 미니 Piezocone의 관입시험이 수행되었으며 그 결과를 비교 분석하였다. 10회의 미니 Piezocone 관입시험이 Ko 조건에서 수행되었으며 33% kaolin, 67% sand mixture가 시료로 사용되었고, 콘관입속도 0.3, 0.6cm/sec, U1(filter element at the cone tip), U2(filter element above the cone base), OCR=1, 10 의 조건이 다양하게 적용되었다. 시험결과 Cone Resistance, Excess Pore Water Pressure, Sleeve Friction 은 U1, U2 두 종류의 콘에 대해서 모두 관입속도가 커짐에 따라 증가하였으나 OCR의 증가에 따라서는 감소하였으며 U1의 Excess Pore Water Pressure가 U2 경우보다 크게 측정되었다.

• 오토저널
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• 제15권2호
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• pp.44-52
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• 1993

In this study, the characteristics of decreasing exhaust gas of diesel engine was examined in dual fuel method by using commertial LPG for automotive. LPG was supplied to engine intake port by fumigation method and flow rate was controlled by using the needle valve. LPG supply ratios were 0, 20, 30% of total fuel amount to be supplied to engine by mass base. We investigated the effect of LPG supply ratio on exhaust gas concentrations related to excess air ratio and engine load at 1600, 1800, 2000 rpm. Soot concentration decreased about 30% in proportion to the increase of the LPG supply ratio. NOx concentration decreased in proportion to the increase of the LPG than diesel only and the increase rate was higher at low engine load. BSFC(Brake specific fuel consumption) was lower in proportion to the increase of the LPG supply ratio at high engine load and to the decrease of LPG supply ratio at low engine load.

• Journal of Korean Neurosurgical Society
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• 제56권3호
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• pp.281-283
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• 2014

McCune-Albright syndrome (MAS) is characterized by a triad of poly/monostotic fibrous dysplasia, caf$\acute{e}$-au-lait macules and hyperfunctioning endocrinopathies including human growth hormone excess. Acromegaly as a manifestation of endocrine hyperfunction with MAS is uncommon. Surgical excision may be challenging due to the associated severe fibrous dysplasia of the skull base. Through the endoscopic procedures, we treated a case of MAS presenting with compressive optic neuropathy due to fibrous dysplasia and acromegaly caused by growth hormone secreting pituitary adenoma. We reviewed the literature on GH excess in MAS to highlight its surgical and medical challenges.

• 대한수의학회지
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• 제25권2호
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• pp.133-144
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• 1985

The changes of acid-base status in vitro of the venous blood for 24 hours in ten Korean native goat were investigated. The acid-base parameters were measured within ten minutes after collection of the blood, and every hour during the first six hours and finally after twenty four hours of storage. Blood samples were stored at two different temperatures ($0-4^{\circ}C$ and $21-24^{\circ}C$). Twelve goats were induced acute acid-base disturbances by intravenous infusion of either hydrochloric acid or sodium bicarbonate and inhalated with $CO_2$ gas mixture (20% $CO_2$, 80% $O_2$) or hyperventilation were performed by means of respirator. The results were as follows; 1. Blood samples could be stored during the first two hours in ice water ($0-4^{\circ}C$) and one hour at room temperature without significant changes in pH. The magnitudes of changes were similar to those of cow, and lower than those of men and dogs. 2. The mean values of acid-base parameters in normal goat were arterial pH, 7.40; $P_{CO_2}$, 35.4mmHg; $HCO_3{^-}$, 21.8mEq/L. 3. Both the base excess and the bicarbonate showed high correlation (r=0.99) during the metabolic disturbance and were represented as $B.E.=1.38\;HCO^-{_3}-29.7$. 4. The slope of blood buffer curve obtained from the in vivo experiment was 16.3mEq/L/pH. 5. The magnitudes of changes in hydrogen ion concentration per unit change of $P_{CO_2}$ were 0.8nM/mmHg in hypercapnia and 1.0nM/mmHg in hypocapnia. 6. The ranges of acid-base parameters in normal goat urine were pH, 6.0-8.1; $P_{CO_2}$, 42-61mmHg; $HCO_3{^-}$, 2-110mEq/L. The concentration of potassium was higher (60-200mEq/L), and that of sodium was lower (8-70mEq/L) than those of human urine.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.26-30
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• 2001

In this paper, transient characteristics of IGBT has been analytically solved to express the excess minority carrier distribution in active base region and the output voltage. Non-Punch Through(NPT) structure has been selected to prove the validity of the model. It is based on the equivalent circuit of MOSFET which supplies a low gain and a high level injection to the base of BJT. None of the quasi static conditions have been assumed to trace the transient characteristics. The basic elements of the model have been derived from the ambipolar transport theory. Theoretical predictions of the output voltages have been obtained with different lifetimes and compared with experimental and theoretical results available in the literature. From the analytical approach, good agreement has been obtained to provide reliable and fast output of the device.

• Journal of Communications and Networks
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• 제15권4호
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• pp.338-351
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• 2013

Multiple-input multiple-output (MIMO) communication may provide high spectral efficiency through the deployment of a very large number of antenna elements at the base stations. The gains from massive MIMO communication come from the use of multi-user MIMO on the uplink and downlink, but with a large excess of antennas at the base station compared to the number of served users. Initial work on massive MIMO did not fully address several practical issues associated with its deployment. This paper considers the impact of channel aging on the performance of massive MIMO systems. The effects of channel variation are characterized as a function of different system parameters assuming a simple model for the channel time variations at the transmitter. Channel prediction is proposed to overcome channel aging effects. The analytical results on aging show how capacity is lost due to time variation in the channel. Numerical results in a multicell network show that massive MIMO works even with some channel variation and that channel prediction could partially overcome channel aging effects.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.25-28
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• 2000

In this study, Transient Characteristics of the Punch-Through Insulated Gate Bipolar Transistor (PT-IGBT) has been studied. On the contraty to Non-Punch Through Insulated Gate Bipolar Transistor(NPT-IGBT), PT-IGBT has buffer layer It has a simple drive circuit controlled by the gate voltage of the MOSFET and the low on-state resistance of the bipolar junction transistor. In this paper, the transient characteristics with temperature of the PT-IGBT has been analyzed analytically. PT-IGBT is made to reduce switching power loss. Excess Minority carrier distribution inactive base region and base charge, the rate of voltage with time is expressed analytically to include buffer layer.

• Journal of Korean Neurosurgical Society
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• 제56권2호
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• pp.135-140
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• 2014

Objective : Propofol and volatile anesthesia have been associated with metabolic acidosis induced by increased lactate. This study was designed to evaluate changes in pH, base excess (BE), and lactate in response to different anesthetic agents and to characterize propofol infusion-associated lactic acidosis. Methods : The medical records of patients undergoing neurosurgical anesthesia between January 2005 and September 2012 were examined. Patients were divided into 2 groups : those who received propofol (total intravenous anesthesia, TIVA) and those who received sevoflurane (balanced inhalation anesthesia, BIA) anesthesia. Propensity analysis was performed (1 : 1 match, n=47), and the characteristics of the patients who developed severe acidosis were recorded. Results : In the matched TIVA and BIA groups, the incidence of metabolic acidosis (11% vs. 13%, p=1) and base excess (p>0.05) were similar. All patients in the TIVA group who developed severe acidosis did so within 4 hours of the initiation of propofol infusion, and these patients improved when propofol was discontinued. Conclusions : The incidence of metabolic acidosis was similar during neurosurgical anesthesia with propofol or sevoflurane. In addition, severe acidosis associated with propofol infusion appears to be reversible when propofol is discontinued.

• 대한임상독성학회지
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• 제13권2호
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• pp.87-94
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• 2015

Purpose: We investigated comparison of clinical characteristics and prognosis by initial endoscopic severity in caustic injury and then discussed predisposing factors which can be helpful in predicting the prognosis and determining the treatment. Methods: This study was a retrospective review of medical records from patients over the age of 15, who underwent initial endoscopy for caustic injury from April 2007 through November 2014. Patients were classified according to two groups based on the initial endoscopic finding by Zargar's classification: patients with grade 0, I, IIa at esophagus (low risk group) and patients with grade IIb, IIIa, IIIb at esophagus (high risk group). The two groups were then compared. Results: A total of 55 patients were included (low risk group [n=44] vs. high risk group [n=11]). Old age (p<0.001), large amount of ingestion (p<0.05), oropharyngeal symptoms (p<0.01), high SOFA score (p<0.001), high WBC count (p<0.05), low base excess (p<0.01), and HCO3 (p<0.05) were statistically significant factors in the high risk group. A poor prognosis was observed for hospital stay (p<0.001), ICU admission (p<0.001), mortality (p<0.01), and stricture (p<0.001) in the high risk group. Conclusion: Clinical characteristics including age, amount of ingestion, oropharyngeal symptoms, SOFA score, WBC count, base excess, and $HCO_3$ can be helpful in the decision to undergo initial endoscopy and risk assessment by initial endoscopic severity can be helpful in predicting prognosis and determining the treatment plan.

• 대한임상독성학회지
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• 제3권1호
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• pp.27-32
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• 2005

Purpose: The frequency of carbon monoxide poisoning has been decreased in the interior of the Korea. But occasionally it is occurred and the risk of exposure is high in working place so far. Because of the characteristics of gas, the detection of exposure and poisoning could be delayed and fatality is high. We should apprehend of carbon monoxide poisoning. So we would report analysis of patients with carbon monoxide poisoning. Methods: A retrospective review of CO poisoned patients visited emergency department from January 2000 to December 2004 was conducted. Results: 24 patients were enrolled. Their average of age was $37.6\pm20.9$ years old and COHb was $19.4\pm13.32\%$. The blood level of initial COHb and mental status on arrival were not correlated each other. The blood level of initial COHb and loss of consciousness were not correlated, too. Initial electrocardiography (EKG) was not correlated with cardiac enzymes such as CK-MB and troponin I. But base excess was correlated with mental status on arrival and complication such as rhabdomyolysis. Hyperbaric oxygen therapy was correlated with base excess and mental status on arrival. Conclusion: The clinical features of carbon monoxide poisoning are nonspecific. For proper diagnosis, it is important that we should consider patient's environment and take patient's history carefully. The blood level of initial COHb does not reflect severity of poisoning accurately. So We should determine the treatment of choice depending on patient's status.