• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2007년도 추계학술발표회
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• pp.133-137
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• 2007

An experimental study is conducted to evaluate and compare the use of BiodieseDI Fuel supplements at blend ratio of 10/90(BDF10) and 20/80(BDF20), in four stroke, direct injection diesel engine located at the authors' laboratory. especially this Biodiesel is produced from Rape oil at the authors' laboratory. The tests are conducted using each of the above fuel blends, in the engine working at a speed of 1800rpm and at a various loads. In each test, specific fuel consumption, exhaust emissions such as nitrogen oxides(NOx), carbon monoxide(CO) and Soot are measured. The results of investigation at various operating conditions are as follows (1) Specific fuel consumption is increased average 1.52%, maximum 1.84% at load 25% in case of BDF10, and average 1.98%, maximum 2.80% at load 25% in case of BDF20. (2) CO emission is decreased average 5.14%, maximum 6.09% at load 0% in case of BDF10, and average 7.75%, maximum 9.13% at load 0% in case of BDF 20. (3) NOx emission is increased average 2.97%, maximum 3.74% at load 0% in case of BDF10, and average 3.84%, maximum 4.67% at load 0% in case of BDF20. (4) Soot emission is decreased average 9.36%, maximum 10.85% at load 75% in case of BDF10, and average 11.99%, maximum 13.95% at load 75% in case of BDF20.

• 한국인터넷방송통신학회논문지
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• 제20권2호
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• pp.157-163
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• 2020

최근 국내에서 미세먼지로 인해 심혈관계 질환이 유발되는 것으로 알려져 운전자들은 대기오염을 일으키는 자동차의 연료를 효율적으로 사용하여 배출 가스를 감소시키는 방안에 대한 관심이 높아지고 있다. 이에 따라, 연비운전으로 연료를 절약시키고 운전자의 잘못된 운전습관을 개선하는 운전 보조 시스템을 개발했다. 개발한 시스템은 라즈베리파이, 아두이노와 안드로이드를 사용했다. OBD-II에서 얻어지는 차량의 RPM, 속도, 연료 분사량 정보들과 자이로센서의 값들을 이용하여 사용자로 하여금 Fuel-Cut을 유도하여 최적의 관성주행 환경을 유도한다. 뿐만 아니라 GUI와 음성인식기능을 통해 날씨, 주행환경, 졸음운전 방지 등 여러 가지 인포테이먼트 시스템을 제공한다. 안드로이드 애플리케이션을 이용하여 주행 기록 및 차량 고장 정보를 확인 할 수 있으며 IoT환경에 최적화 된 MQTT 프로토콜을 사용하여 메시지 전송의 오버헤드가 적게 구현했다.

• 에너지공학
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• 제18권2호
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• pp.87-92
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• 2009

본 논문은 안쪽축이 회전하는 동심환형관 물과 비뉴튼유체의 고-액 2상 유동연구를 수행하였다. 점탄성유체의 유변학은 굴착구멍의 청결, 입자의 밖으로 수송하는 등 여러 가지 응용에 중요하다. 연구에서 투명한 아크릴관은 고체입자의 이동을 관찰하기 위하여 사용하였다. 환형관 속도는 0.3m/s에서 2.0m/s로 변한다. 머드시스템은 물과 CMC 수용액을 혼합하여 사용하였다. 연구에서 고려된 주요 변수들은 축회전속도, 유체 유동영역과 입자 주입율이다. 입자이송속도와 압력강하는 유체유량(Q, LPM)이 5~30의 범위에서 측정하였다. 물과 0.2% CMC 수용액에서 고체입자의 농도가 높을수록 압력손실이 커짐을 알 수 있었다.

• 상하수도학회지
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• 제14권1호
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• pp.54-61
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• 2000

Recently, our circumstances are threatened by an accident that leakage of under ground storage tank and illegal dumping of synthetic organic compounds at chemical plants and many treatment methods, Activated carbon adsorption, Ozonization, Membrane filtration and Photocatalystic oxidation, are developed to remove such a synthetic organic compounds. And it has reported that Activated carbon adsorption have a great removal efficiency to nondegradable matters and organic compounds which have a high molecular weight. Comparing with other adsorbents, Activated carbon adsorption have a worse efficiency when ad desorption speed is low. Thus improved type of adsorbents was invented and one of those is Activated Carbon Filter. The purpose of this study was getting information about adsorption characteristic phenol which can be applied Activated Carbon Fiber and Granular Activated Carbon. In detail, With comparing removal characteristics of phenol in the presence Humic Acid using Activated Carbon Fiber(ACF) and Granular Activated. Carbon(GAC), it is to certify an effective application of Activated Carbon Fiber. At the range of this study, Batch test, Isotherm adsorption test and Factorial analysis, following conclusion were obtained from the results of this study. Batch test was carried to know time of adsorption equilibrium. In this study about time of adsorption equilibrium by ACF was faster than GAC's, for developed micropore of ACF. From the result of phenol adsorption test, High removal rate of adsorption is shown at pH 5. The result of lsotherm adsorption test, it has represented that the Freundlich's isotherm is most suitable one in others, that a ACF's adsorption capacity is more excellent than GAC's. Adsorption of phenol exiting humic acid is decreased getting raised humic acid concentration. Since ACF's micropore is developed at this time, an effect of high molecular humic acid is lower. Factorial analysis was carried to know about Main effect which was injection dosage of adsorbent in the range of this study.

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1050-1056
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• 2010

디젤기관은 공기만을 흡입 압축한 후에 연료를 분사하여 연소하기 때문에 높은 압축비가 가능하다. 높은 압축비에 의한 고효율의 장점과 연료의 직접분사에 의한 매연미립자의 배출 및 질소산화물의 배출이 많은 단점을 갖고 있다. 이러한 문제점을 해결하기 위하여 많은 연구들이 진행되었으며 수소를 흡기중에 공급하는 기술도 연구되고 있다. 본 논문에서는 미량의 수소를 연소실에 공급하여 엔진성능에 미치는 영향을 평가하였다. 토크와 엔진속도를 100%, 75%, 50%, 25%, 0%와 700rpm, 1000rpm, 1500rpm, 2000rpm로 구분하여 실험하였다. 실험결과 질소산화물이 약간 증가하였지만 연료소비율, 스모크와 일산화탄소 배출은 감소하였다. 수소의 첨가는 저부하 영역에서는 효과가 거의 없었지만 고부하 영역에서 큰 효과가 있었다.

• 한국주조공학회지
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• 제14권5호
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• pp.471-479
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• 1994

Al-2%Si-2%Mg alloy containing SiC particle in 20, $70{\mu}m$ were prepared by mean of squeeze casting with various pressure 50, 100, 150 and 220MPa respectively. The specimens were made by casting into $50{\Phi}{\times}100{\ell}$ mold under various squeeze conditions(pressures, pressurizing temperature, particle sizes). Mechanical properties(hardness, tensile strength, elongation and wear characteristics) were evaluated at room temperature with those various fabrication factors. It became feasible to make favorable Al-SiCp composite free from casting defects by the injection of Ar gas during melting and 100MPa pressure squeeze casting. However, pressure of 50MPa was not sufficient to avoid completely porosity formation as a result of precessing and shrinkage during solidification. As the particle size is smaller and the squeeze pressure is higher, the hardness and tensile strength at room temperature are higher. Cell size became smaller gradually with increase of squeeze pressure. With increase of squeeze pressure(MPa), wear behaviors of those composites were changed from adhesive into abrasive wear, and the tendency of above behavior became outstanding with increasing sliding speed. The chemical reaction(4Al＋3SiC${\rightarrow}$$Al_4C_3+3Si$) is more accelerated at interface between SiCp and matrix with increase of squeeze pressure. Therefore $Al_4C_3$ intercompound and Si peak intensity is increased at interface.

• 한국자동차공학회논문집
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• 제22권2호
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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.

• The Korean Journal of Pain
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• 제8권1호
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• pp.37-42
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• 1995

The intermittent injection of analgesics is a inadquate method for postoperative pain control. Recently a non-electroic, disposable and portable infusor (Boxter Two Day $Infusor^R$) has been developed which can deliver analgesics with 2 ml/h speed continuousely. The present study examined the effects of three methods of pain management on recovery in 306 patients undergoing elective surgery in Wonkwang University Hospital. Group 1 (n=106) received i.m. $Valentac^R$ on a PRN basis. Group 2 (n=100), initial 2 mg of bolus morphine was followed by 48 mg of continuous infusion. Group 3 (n=100), initial 2 mg of morphine followed by morphine 18 mg-ketorolac 120 mg. We evaluated an analgesic efficacy with NRS (numerical rating scale) at 12, 24, 36, 48, 60 and 72 hours after the operation. The side effects (nausea, vomiting, pruritus, sedation and respiratory depression) were evaluated. In group 1, we asked major concern before operation and efficacy of pain control with pain severity (no pain, mild pain, moderate pain, sever pain). The results were as follows: 1) Major concern before operation is pain (40%). 2) 53% of patients suffered pain in group 1. 3) Morphine and morphine-ketorolac infusion groups were superior to the i. m. ($Valentac^R$) group with respect to postoperative analgesia. 4) In group 3 (morphine-ketorolac), there was no pruritus and mild nausea and vomiting.

• 대한디지털의료영상학회논문지
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• 제16권1호
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• pp.27-33
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• 2014

The purpose of this study evaluated the hemo-dynamic information within 30 seconds clinically in 3D breast MRI. From January to March 2014, A total of 40 people were examined at 1.5 Tesla(Philips, Medical System, Achieva, The Netherlands) MRI equipments using 16 channel SENSE breast coil. The imaging parameters on vibrant are fellow as: $TR/TE/FA^{\circ}$/Matrix size/Slice thickness/Slab($5ms/2ms/10^{\circ}/180{\times}139{\times}2mm/80$). This study used a Gadovist and injected it with injection speed of 4 ml /sec by auto injector with 15 ml saline flushing. Firstly, for the delay time study, it divided three different delay time from immediately, 20 seconds, and 30 seconds. In quantitative analysis, the ROI signal intensities of tumor and surrounding tissues were measured retrospectively. In qualitative analysis, the image quality was scored from 1 to 5 point by one experienced radiological technologists as a visual test. The significance level of each delay time was evaluated with a one-way ANOVA(p<0.05). In the visual test, score levels on 30 seconds delay time was a little bit higher than others(p<0.05). The signal intensity of the tumor were $1445{\pm}360$, $1410{\pm}320$, $1510{\pm}415$ on immediately, 20 seconds, and 30 seconds and score levels were $4.18{\pm}0.85$, $3.54{\pm}0.94$, $4.45{\pm}0.74$(p<0.05). The data on immediate images showed better results than that others(p<0.05). Conclusively, Although it has been high scored in 30sec delay time for visual test in order to avoid failure in 20second, 30seconds delay time after contrast media administration, we recommend that the DCE 3D breast MRI commence immediately.

• 한국유체기계학회 논문집
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• 제10권6호
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• pp.32-37
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• 2007

Aerodynamic forces and moments have been used to control rocket propelled vehicles. If control is required at very low speed, Those systems only provide a limited capability because aerodynamic control force is proportional to the air density and low dynamic pressure. But thrust vector control(TVC) can overcome the disadvantages. TVC is the method which generates the side force and roll moment by controlling exhausted gas directly in a rocket nozzle. TVC is classified by mechanical and fluid dynamic methods. Mechanical methods can change the flow direction by several objects installed in a rocket nozzle exhaust such as tapered ramp tabs and jet vane. Fluid dynamic methods control the flight direction with the injection of secondary gaseous flows into the rocket nozzle. The tapered ramp tabs of mechanical methods are used in this paper. They installed at the rear in the rocket nozzle could be freely moved along axial and radial direction on the mounting ring to provide the mass flow rate which is injected from the rocket nozzle. In this paper, the conceptual design and the study on the tapered ramp tabs of the thurst vector control has been carried out using the supersonic cold flow system and schlieren system. This paper provides the thrust spoilage, three directional forces and moments and distribution of surface pressure on the region enclosed by the tapered ramp tabs.