• Journal of Biosystems Engineering
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• v.20 no.3
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• pp.226-235
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• 1995

An unmanned speed sprayer was developed using a remote control and an inductive cable guidance systems to protect operators and environment from hazardous pesticides. The sprayer consists of a remote control system, an induction system, obstacle detectors, control actuators and an one-chip microcomputer. The sprayer can be operated by the induction guidance and/or remote control. The following summarize characteristics of the developed speed sprayer. 1) Both the remote control and the induction guidance operation were possible with the developed speed sprayer. 2) Sixteen functions of the forwarding, backing, halting, steering, 3-way valve for nozzles and fan operating etc. were utilized on the remote control system. 3) It was concluded that the DTMF method, having less transmitting error, performed better than the FSK method for an agricultural remote controller. A radio station may be necessary. 4) The digital inductive guidance system, consisting of five low-impedance detection coils and a window comparator circuit, performed better than the analog detecting system, guiding route using inductive voltage differential from tow detection coils.

• Journal of Chest Surgery
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• v.28 no.6
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• pp.565-570
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• 1995

Seventy-three patients with isolated total anomalous pulmonary venous connection the patients associated with other major cardiac anomalies such as single ventricle, DORV[Double Outlet Right Ventricle and large VSD[Ventricular Septal Defect were excluded were underwent surgical repair from January 1980 through October 1993. There were 45 boys and 28 girls. The mean age at operation was 19.9 months[range 6 days to 24 years and mean body weight was 7.1kg[range 2.6kg to 45kg . The anomalous locations of connection were supracardiac in 38, cardiac in 21, infracardiac in 5, and mixed in 9. In 38 patients[52% , the venous drainage was obstructed. The obstruction ratios according to the connection type were as follows: 53%[28/38 in supracardiac, 52%[11/21 in cardiac, 100%[5/5 in infracardiac, 22%[2/9 in mixed type. The associated cardiac anomalies were persistent left SVC[2 , tricuspid valve regurgitation[3 , cor triatriatum[1 , and mitral cleft[1 . And associated noncardiac anomalies were imperforate anus[1 and Neil Weightman syndrome[1 . The operative mortality was 23%. The causes of death were pulmonary hypertensive crisis, perioperative myocardial failure, pneumonia with sepsis, arrhythmia and etc. The statistically significant factors in postoperative mortality were the pulmonary venous obstruction and age [p<0.01 . The operative mortality was high in groups of age under 1 month and pulmonary venous obstruction. The mean follow-up was 27.1 months. There were two late deaths. The first patient was three months old boy with supracardiac type and severe obstructive symptoms. The postoperative echocardiography was showed anastomotic stenosis and reoperations were performed twice but the patients expired due to pneumonia and sepsis. The second patient was three month old boy with supracardiac type and total correction was done and was doing well postoperatively. Eight years later, he expired suddenly due to arrhythmia. But all the other patients were in NYHA Fc I and received no medications. The 5-year survival rate excluding early expired patients is 97.1 $\pm$ 0.03 %. In conclusion, although the operative mortality of total anomalous pulmonary venous connection was relatively high compared to other major cardiac anomalies, we could expect excellent long-term results by early surgical correction.

• Journal of the Korean Institute of Gas
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• v.12 no.1
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• pp.31-35
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• 2008

Natural gas vehicles are being applied to city buses for improving air quality in metropolitan and have proved the effective way to reduce the pollutant emissions. Liquified Natural Gas(LNG) has also attempted a vehicle fuel in order to raise the fuel storage density that is a disadvantage of Compressed Natural Gas(CNG). This paper described insulation characteristic of a LNG storage tank. From the results, adiabatic coefficient of a tested tank was around $40J/h{\cdot}^{\circ}C{\cdot}m^2$ and it was the lower level than gas safety regulation limit. Two experimental methods were adopted to justify the evaluation results and they were revealed that the results were very similar to each other. Also, through testing relief valve operation characteristic it was investigated venting amount of boiled off gas.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.1
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• pp.37-47
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• 2002

Recently gasoline direct injection method has been applied to gasoline engine to reduce fuel consumption rate by controlling fuel air mixture on lean condition by means of stratified charging, and to reduce simultaneously. Pollutant emissions especially NOx and CO by lowering the combustion temperature. But difficulty of controling local fuel air ratio at ignition area in flammability limit unavoidably appeared, because it is merely controlled by injection timing with spatial and temporal distribution of fuel mixture. In this study, the authors devised a uniquely shaped combustion chamber so called three-chamber GDI engine, intended to keep the more reliable fuel air ratio at ignition area. The combustion chamber is divided into three regions. The first region is in the rich combustion division, where the fuel is injected from the fuel injection valve and ignited by the spark plug. The second region is in the lean combustion division, where the combustion gas from the rich combustion division flows out and burns on lean condition. And the last region is in the main combustion division ie in the cylinder, where the gas from the above two combustion divisions mixed together and completes the combustion during expansion stroke. They found that the stable range of operation of three-chamber GDI engine on low-load condition exists in the lean area of average equivalence ratio. And they also found that the reformed engine reveals less specific fuel consumption and less pollutant emissions compared with conventional carburettor type gasoline engine.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.893-904
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• 2013

In this paper, a Kriging metamodel-based multi-objective optimization strategy in conjunction with an NSGA-II(non-dominated sorted genetic algorithm-II) has been employed to optimize the valve-plate shape of the axial piston pump utilizing 3D CFD simulations. The optimization process for minimum pressure ripple and maximum pump efficiency is composed of two steps; (1) CFD simulation of the piston pump operation with various combination of six parameters selected based on the optimization principle, and (2) applying a multi-objective optimization approach based on the NSGA-II using the CFD data set to evaluate the Pareto front. Our exploration shows that we can choose an optimal trade-off solution combination to reach a target efficiency of the axial piston pump with minimum pressure ripple.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.156-165
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• 2014

This paper is the first investigation on the effect of flow control methods on the part load performance in a spark ignition engine. For comparison of the methods, two control devices, port throttling and masking, were applied to a conventional engine without any design change of the intake port. Steady flow evaluation shows that steady flow rates per unit opening area and swirl ratio are very low compared with the port throttling and saturated from mid-stage valve lift, however, swirl increases slightly as the lift is higher in case of 1/4 masking control. In the part load performance, the effect of simple port throttling on lean misfire limit expansion is limited and insufficient; on the other hand a masking improves the limit considerably without any port modification for increasing swirl. Also the results show that the intake flow control improves the combustion with following two mechanisms: stratification induced by the combination of the flow pattern and the fuel injection timing attribute to ignition ability and the intensified flow ensure fast burn. In addition fuel consumption reduces under the flow controls and the reduction rate is different according to the operation conditions and control methods. At the Stoichiometric and/or low speed and low load the throttling method is more advantageous; however vice versa at lean and high load condition. Finally, the throttling is more efficient for HC reduction than masking, on the other side the NOx emissions increase under the masking and decrease under the port throttling compared with conventional port scheme.

• Journal of Astronomy and Space Sciences
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• v.19 no.3
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• pp.207-214
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• 2002

One of the way to derive design parameters of the fuel feeding system in satellite propulsion system is to analyze unsteady flow of liquid propellant (hydrazine). During steady thruster firing the flow rate is constant: if a thruster valve is abruptly shut down among a set of thrusters, pressure spikes much higher than the initial tank pressure occur. This renders the fuel flow unsteady, and the fluid pressure and flow rate to oscillate. If the pressure spikes are high enough, there are possibilities that propellant explosively decomposes, thruster valves we damaged, and adiabatic detonation of the hydrazine propellant is potentially incurred. Reflected shockwaves could also affect the calibration and operation of the pressure transducers. These necessitate the analysis of unsteady flow in the propulsion system design, and pressure behavior inside the propellant line obtained through some governing parameter variation is presented in this work.

• Journal of Chest Surgery
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• v.14 no.3
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• pp.260-267
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• 1981

Left atrial myxoma is a rare disease and its recurrence is reported to be always possible whenever primary excision is incomplete. Cardiac Myxoma is rare disease of the heart, and it has a little chance of recurrence. We experienced a patient of recurrent left atrial myxoma who was 31 years old, had been gotten excision of Lt. atrial myxoma when she was 28 years of her age. She was gotten mitral valve replacement simultaneously during 2nd operation with difficulty. So we report this case with the review of the literatures. [KTCS 1981;3:260-267]Surgical Treatment of Acute Pyogenic Pericarditis followed the Sepsis Ki Woo Shin, M.D.,* Ho Wan Lee, M.D.* and Dong Jun Lee, M.D.* Two cases of acute pyogenic pericarditis are, one case, 12-year-old male patient, followed the bacteremia of pneumonia and other case, 9 year old female patient, followed the bacteremia of osteomyelitis. After the confirmed diagnosis by pericardial aspiration, the emergency pericardial window was made to relief the severe cardiogenic symptoms. The general symptoms were improved immediately, but 40 days and 15 days after pericardiostomy, in each case, the sign and symptoms of cardiac compression were seen with recurrent cardiac tamponade. Pericardiectomy with median sternotomy was performed in each case and thereafter the patients were discharged without any problems.

• Journal of Chest Surgery
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• v.29 no.2
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• pp.185-190
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• 1996

The effect of low-dose aprotinin on hemostasis in patients undergoing cardiopulmonary bypass (CPB) for repeat valve replacement and coronary artery bypass operations were investigated. Thirty patients undergoing elective CPB from February 1993 through February 1995 at Catholic Medical Center were studied. the patients were randomly divided into two groups(15 patients per group) : group 1, receive 1, 000, 000 KIU/kg aprotinin in the CPB priming volume and 20, 000 KIU/kg aprotinin intravenously each hour during CPB ; group 2, without aprotinin administration served as the controls. The result showed that the early postoperative (during the first 24 hours) and mean postoperative total blood loss of the aprotinin group were significantly reduced than the control group (317.2 $\pm$ 89.6ml in the aprotinin group versus 821.3 $\pm$ 441.2rnl in the control group, p<0.01 ; 767.2 $\pm$ 214.1 ml in the aprotinin group versus 1562.5 $\pm$ 735.2 rnl in the control gorup, p<0.01). Total use of packed red ells and fresh frozen plasma was higher in control group(1.22 $\pm$ 0.3 units versus 4.21 $\pm$ 1.7units of packed red cells, p<0.01 : and 2.37 $\pm$ 0.4units versus 6.72 $\pm$ 0.88uni1s of fresh prozen plasma, p<0.05). We conclude the low-dose aprotinin was positive influence on postoperative blood loss in undergoing highly bleeding potency cardiac operation.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.388-392
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• 2007

지구온단화와 이상기후에 의해 시설물 피해가 나날이 증가하고 있으며, 농촌의 인구감소 및 고령화에 의해 이러한 집중강우등에 대한 대처도 어려운 실정이다. 현재 전국에서 농업용수 공급을 위해 사용하고 있는 농업용 저수지는 17,882개소로서 이 중 축조한지가 35년 이상 경과된 저수지가 15,856개소로서 88.7%나 차지하고 있다. 이러한 현상은 저수지를 구성하고 있는 각종 부대시설의 노후화로 귀결되며 농업용수의 낭비 및 효율적인 운영을 위해서는 시설의 현대화가 필수적이라고 할 수 있다. 따라서 본 연구에서는 저수지에서 물을 직접 공급하는 시설인 사통수문을 대상으로 현대화를 이룩하고 또한 사용동력도 대체에너지를 이용하기 위한 방안을 제시하였다. 사통수문의 수문비는 수중의 압력을 효율적으로 분산시킬 수 있는 원형수문비와 수중에서도 사용동력을 가장 적게 할 수 있는 밸브형을 기준으로 개발을 하였으며, 수문비와 구동부를 연결하는 작동 롯드의 힘전달을 최소화하기 위하여 유니버셜 쪼인트를 볼밸브형으로 개발하였다. 이에 따라서 작동용 롯드의 길이가 길어져도 수문비에 걸리는 작동모멘트를 최소화하여 태양광을 이용한 동력사용이 가능해졌다. 특히 수중에서 움직이는 특성을 감안하여 원형 수문비의 경우에는 수문비와 수문틀 사이에 마찰력을 감소시키기 위하여 수문틀측을 약간 경사지게 가공을 하고 중간에 볼 베이렁을 부착시켜 수문개폐가 원활토록 지수부의 구조변화를 하였다. 또한 농업용수공급시 수류와 함께 유입되는 저수지 내 오물을 차단하기 위하여 수문의 전면에 스크린을 설치하였으며 토사퇴적으로 인하여 수문작동의 방해가 되지 않도록 하기 위하여 토목구조물을 설치하였다. 그리고 동력전달을 효율적으로 하기 위하여 Solar Unit으로부터 나오는 전기를 중전기에서 밧데리로 축전을 시키고 완전 충전 후에는 나머지 전기는 방전이 되도록 회로를 구성하였다. 사통수문 자원조사 결과에 의하면 현재 저수지에 물공급을 하는 수문은 취수탑 형식이 70% 이상을 차지하고 있으며 나머지 30%의 사통수문 중 원형수문비가 98% 이상을 차지하고 있다. 현재 대체에너지를 사용하는 저수지 사통수문은 없는 것으로 조사되었으며 전력을 사용하는 사통도 조사결과에 의하면 20% 이내로 나타났다. 이러한 결과는 향후 수리시설 개보수시 적은 예산으로 사업을 시행하는 경우 사통수문의 설치방향의 지표가 될 것으로 판단되며 수리시설의 운영관리에 대한 새로운 대안으로 제시할 수 있다.