• Journal of the KSME
• /
• v.30 no.6
• /
• pp.564-571
• /
• 1990

최근의 기관은 DOHC 또는 SOHC로 4밸브나 5밸브를 채용하여 흡기계의 효율향상을 시도하고 있다. 그러나 고속성능에 중점을 두고 기관제원을 설정하게 되면서 저속 실용역에서 토크의 저하를 초래하는 경우가 많아지고 있으며 금후 이러한 문제의 해결에 많은 노력이 계속될 것으로 전망된다. 또한 전자기술의 발전과 자동차에 대한 적용 기술이 향상됨에 따라 앞으로 가변흡기 시스템, 가변밸브 타이밍, 가변 터보, 가변 기통수, 가변 압축비등 가변기술에 대한 연구개발이 더욱 활발히 이루어질 것이다.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.8
• /
• pp.1009-1015
• /
• 2011

In this study, in the high expansion cycle was conduced by variable valve timing system composition to close intake valve late, and in the intake air reduction on the low compression was solved by supercharging pressure. In this wise, by constituting Diesel-Atkinson cycle, this study looked into a possibility of thermal efficiency improvement. As a result, there was improvement in thermal efficiency and output in a whole range of closing timing from ABDC $40^{\circ}$ to ABDC $80^{\circ}$. However, after ABDC $70^{\circ}$ of closing timing, the thermal efficiency increase was getting smaller. As the result of the study, the optimum intake valve closing timing was about ABDC $70^{\circ}$, high loading territory of engine was more effective than low loading territory, and engine operation in middle loading territory was stable. At this time, brake thermal efficiency was 12.5% higher than ordinary engine on average.

• Journal of the korean Society of Automotive Engineers
• /
• v.6 no.1
• /
• pp.1-10
• /
• 1984

1982년 8월에 Toyota가 전자제어시스템을 갖춘 새로운 디이젤기관을 선보였다. 이 제어시스템 들은 연료의 분사량, 분사시간, 아이들링속도, 글로우 플러그(glow plug)전류 및 흡기량의 최적 제어를 할 수 있도록 하였다. 이로써 높은 기관성능, 즉 훌륭한 연료절약효과와 양호한 운전성 능에 기관의 소음이나 진동의 저감 등에 큰 이점들을 얻을 수 있게 된다.

• Journal of Energy Engineering
• /
• v.13 no.2
• /
• pp.118-127
• /
• 2004

The purpose of this study is experimentally to analyze that intake port swirl, injection system and turbocharger have an effect on the engine performance and the emission characteristics in a V8 type turbocharged intercooler D.I. diesel engine of the displacement 16.7ι, and to suggest the improvement of engine performance. Generally to enhance engine power, TCI diesel engine is put to practically use turbo-charged intercoler in order to increase boost efficiency which is cooled boost air. As results of considering the factors of the intake port of swirl ratio 2.25, compression ratio 17.5, re-entrant 8.5$^{\circ}$ combustion bowl, nozzle hole diameter ${\Phi}$0.33*3+${\Phi}$0.35*2, nozzle protrusion 3.18mm, injection timing BTDC 12$^{\circ}$CA and turbo charger (compressor 0.6A/R+46Trim, turbine 1.0A/R+57Trim) is the best in the full range of operating in the engine performance and the exhaust characteristics of NO$\_$x/ concentration. Therefore their factors are appropriated as intake system, injection and turbocharger system.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.6
• /
• pp.106-114
• /
• 1999

Today, one of the most important objective in automobile development is to reduce the weight of automobile . The eventual depletion of petroleum and environmental regulations brought considerable emphasis to this area on increasing fuel efficiency. Conventional intake air-fuel system is very heavy because it is composed of numerous parts. The bulky size caused increase in the amount of metal being used to build automobile chassis and this became a serious weight problem. The size also caused difficulties in optimization of fuel supply system which in turn decreased engine efficiency. Currently , there are efforts to integrate several intake system modules into one. The purpose of this paper is to evaluate the directions of such development.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.25 no.6
• /
• pp.788-794
• /
• 2019

Recently, global climate change caused by greenhouse gases has emerged as a significant air-environmental problem. Technical innovation in response to this phenomenon is ongoing, with an emphasis on the environmental impacts of unusually high temperatures and unexpected heavy rainfall. In this study, we investigated the effects of temperature change on air pollution for a concomitant rapid temperature increase. The test conditions include loading from 0 % to 100 % at 1400 rpm, 1600 rpm, and 1800 rpm for a change in the intake air temperature of a marine diesel engine from 20 ℃ to 50 ℃. The experimental results revealed that CO and HC decreased slightly, whereas the brake specific fuel consumption, NOx, and PM increased slightly when the intake air temperature changed. In addition, it was determined that the combustion temperature did not change significantly.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.8
• /
• pp.1100-1106
• /
• 2009

Recently, there are quite a lot of attention is drown on the researches related to of Miller method applied high expansion cycle. For this study, high expansion cycles are formed and analyzed with the base view point of thermodynamics, and the features of each factors are also investigated. As a result of analysis, the expansion-compression ratio is expected with a decrease of effective compression ratio as intake valve closing time retarded, however, the decrease of mean effective pressure and its output is accompanied with the counterflow of intake air. Accordingly, as the consequence of such failure, it is expected that an alternative is needed for the realization of high expansion cycles, and the improvement over thermal efficiency. To materialize such cycle, the control system to delay the closing time of intake valve was designed and VVT, the 3 S/B low speed diesel engine, is applied to evaluate the efficiency. The result of the trial shows that there was no significant errors.

• Journal of Veterinary Clinics
• /
• v.30 no.1
• /
• pp.32-35
• /
• 2013

Six English Bull dogs from the same dog training camp were referred with main complaints of stridor, gagging and coughing. Diagnostic imaging studies on these dogs revealed hypoplastic trachea with/without bronchopneumonia. The mean age of affected dogs was $4.83{\pm}2.63$ months, while the mean body weight was $9.03{\pm}5.30$ kg. The mean ratio of the tracheal diameter to the thoracic inlet distance (TD/TI) was $0.085{\pm}0.022$ (normally 0.16 or greater), whereas the mean ratio tracheal diameter to the width of the third rib (TD/W3R) was $1.36{\pm}0.36$ (normally 2 or greater). All dogs had marked inspiratory dyspnea with variable degree of coughing. Of 6 dogs, 4 dogs had either bronchitis or bronchopneumonia. Treatment with antibiotics and bronchodilators made improvement on clinical signs on these dogs. Although some dogs still had mild inspiratory dyspnea (especially after exercise or excitement), most dogs live normally.

• Tuberculosis and Respiratory Diseases
• /
• v.57 no.5
• /
• pp.434-438
• /
• 2004

Background : An excessive endotracheal cuff pressure can cause tracheal injury, and insufficient cuff pressure may not generate an effective cuff seal. The peak inspiratory pressure influences the minimal occlusion pressure of the endotracheal tube cuff. However, the relationship between the minimal occlusion pressure and the tidal volume has not been investigated. This study was conducted to estimate the relationship between the tidal volume and the minimal occlusion pressure of the cuff. Methods : Ten mechanically ventilated patients were included. The minimal occlusion pressure of the cuff was measured using a pressure gauge. The basal tidal volume was increased and decreased as much as 10% whilst maintaining the same peak inspiratory pressure. The, minimal occlusion pressures were then measured in the high and low tidal volume state, respectively. Results : The peak inspiratory pressure was $32.6{\pm}4.72cmH_2O$ and the minimal occlusion pressure was $19.0{\pm}2.26$ mmHg in the basal ventilator setting. There was a significant relationship between the peak inspiratory pressure and the minimal occlusion pressure(r=0.77, p<0.01). The minimal occlusion pressure of the cuff was increased to $20.3{\pm}2.4$ mmHg in the high tidal volume state(p<0.05), and decreased to $16.8{\pm}3.01$ mmHg in the low tidal volume state (p<0.001). Conclusion : The minimal occlusion pressure of the cuff can be influenced by changes in the tidal volume as well as by the peak inspiratory pressure.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.27.2-27.2
• /
• 2005