• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.1031-1035
• /
• 2008

The importance of the more efficient cogeneration system is emphasized. Also the more clean energy is needed at recent energy system. The cogeneration system using Lean burn engine is more preferred to the system using Rich burn engine because of the electrical efficiency. Although the cogeneration system using Lean burn engine is economically preferred, because of the NOx emission level, the system using Rich burn engine with 3-way catalyst can only be used in Korea. The NOx regulation level is 50ppm at oxygen level 13%. The cogeneration hybrid system is consist of Lean burn gas engine, afterburner, boiler, economizer, DeNOx catalyst, combustion catalyst, absorption chiller, cooling tower and grid connection system. The system was accurately evaluated and the result is following ; 90% total efficiency, below 10ppm NOx, 50ppm CO, 25ppm UHC. The cogeneration hybrid system can meet the NOx level and exhaust gas regulation. It can achieve the clean combustion gas and efficient cogeneration system.

• International Journal of Automotive Technology
• /
• v.7 no.5
• /
• pp.519-526
• /
• 2006

For investigating the effect of fuel stratification on flame propagation, initial flame development and propagation were visualized under different axially stratified states in a port injection SI engine. Stratification was controlled by the combination of the port swirl ratio and injection timing. Experiments were performed in an optical single cylinder engine modified from a production engine and images were captured through the quartz window mounted in the piston by an intensified CCD camera. Firstly in this paper, the characteristics under no port-generated swirl condition, i.e. normal conventional case was studied. Under various stratified conditions, flame images were captured at the pre-set crank angles. These were averaged and processed to characterize the flames propagation. The flame stability was estimated by the weighted average of flame area and luminosity. The stability was also evaluated through the standard deviation of flame area and propagation distance, and mean absolute deviation of propagating direction. Results show that stratification state according to injection timing do not affect on the direction of flame propagation. The flame development and the initial flame stability are strongly dependent on the stratified conditions and the initial flame stability is closely related to the engine stability and lean misfire limit.

• Journal of ILASS-Korea
• /
• v.3 no.3
• /
• pp.33-41
• /
• 1998

In recently, a study on the lean combustion is investigated intensively, because it is expected that this method may decrease the harmful exhaust gas and improve fuel economy in gasoline engine. The problems of lean combustion system in gasoline engine are ignition difficulty, misfire and instability of combustion. The investigation on the optimization of fuel metering and the control of mixing gas flow may be critical to improve the performance of lean combustion. In the fuel injection gasoline engine, the formation of mixture influences strongly on the engine performance such that the importance of fuel metering system becomes apparent. First of all, a study on the fuel breakup characteristics of gasoline fuel injector was carried out in this paper. Fuel injectors are pintle and 4hole-2spray type. The purpose of this study is to clarify the atomization mechanism of spray injected into atomosphere field through electronic controlled-fuel injectors, and to analyze spray characteristics such as drop size distribution and mean drop diameter produced at fuel injector. In this paper, the spray development is observed by taking photograps using 80mm still-camera system, and drop sizes are measured by PMAS. From these experiment, spray pattern injected from gasoline fuel injectors was investigated clearly. Also, it was found that SMD and drop size distribution of injected fuel spray from gasoline fuel injectors.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.36 no.2
• /
• pp.225-232
• /
• 2012

A chemical reactor network (CRN) was developed for a lean premixed gas turbine combustor to predict the emission of pollutants such as NOx and CO. In this study, the predictions of NOx and CO emissions from lean premixed methane-air combustion in the gas turbine were carried out using CHEMKIN and a GRI 3.0 methane-air combustion mechanism, which includes the four NO formation mechanisms for various load conditions. The calculated results were compared with experimental data obtained from a modified test combustor to validate the model. The contributions of the four NO pathways were investigated for various load conditions. The effects of nonuniformity of the mass flux and of the equivalence ratio of the injector on the NOx formation were investigated, and a method of reducing the pollutant formation was suggested for the development of a sub-10 ppm gas turbine combustor.

• Information Systems Review
• /
• v.19 no.2
• /
• pp.57-70
• /
• 2017

Researchers and industry managers highlight the emergence of mobile healthcare market given the rapid development of IT and the expansion of average life expectancy. Medical institutions, such as university hospitals, are aiming to achieve convenience and effectiveness of treatment by providing patient education through a mobile device. This study examines a case related to the development and usage of a mobile application based on Lean Canvas, namely, the Smart Explanation Service released by Samsung Medical Center. This application comprehensively analyzes the usage status of mobile application-based patient education and its application in clinical settings. This study also examines the level of satisfaction of patients and medical workers toward this application. The result of this study is expected to provide meaningful implication to medical institutions and related industries and enable them to create and offer prepare mobile healthcare services.

• 한국도로학회:학술대회논문집
• /
• 2011.03a
• /
• pp.153-158
• /
• 2011

• Proceedings of the Korean Society for Quality Management Conference
• /
• 2007.04a
• /
• pp.18-32
• /
• 2007

최적의 혁신기법이란 각사의 핵심역량을 명확히 한 후 꾸준히 그리고 지속적으로 자사에 맞게 시스템(SYSTEM)을 변형해 나가는 과정에서 완성된다고 볼 수 있다. 반도체 제조사인 H사는 지난 IMF 때 경영적인 어려움을 극복하고 최근 각 부문(제조, 연구개발, 영업 등)의 탁월한 경영성과를 올리고 있다. 이러한 성과를 뒷받침하는 것은 경영혁신 활동이 일환으로 TPM을 2001년부터 꾸준하게 적용을 해 오고 있다는 것이다. 일반적으로 TPM은 제조중심의 활동이 대부분이나, H사는 R&D부문 경영혁신 활동에 TPM활동을 접목해 활동을 하고 있다. 본 연구는 H사의 R&D부문 TPM R&D보전의 10대 지주 활동과 연구개발 부문에서 활발하게 연구되고 있는 Lean DFSS의 두 방법론에의 장 ${\cdot}$ 단점을 분석하여 좀 더 바람직한 방법론을 연구해 볼 필요가 있다.

• BMB Reports
• /
• v.43 no.9
• /
• pp.593-598
• /
• 2010

Tetrahydrobiopterin ($BH_4$) is a pivotal cofactor for enzymes responsible for the synthesis and release of monoamine neurotransmitters including dopamine and serotonin as well as the release of glutamate. Deficiencies in $BH_4$ levels and reduced activities of $BH_4$-associated enzymes have been recently reported in patients with schizophrenia. Accordingly, it is possible that abnormalities in the biochemical cascades regulated by $BH_4$ may alter DA, 5-HT and Glu neurotransmission, and consequently contribute to the pathophysiology of different neuropsychiatric diseases including schizophrenia. The development of a novel strain of mutant mice that is deficient in $BH_4$ by knocking out the expression of a functional sepiapterin reductase gene (spr -/-) has added new insights into the potential role of $BH_4$ in the pathophysiology and improved treatment of schizophrenia.

• Journal of the Korean Society of Safety
• /
• v.7 no.3
• /
• pp.3-13
• /
• 1992

In recent years, the study about the high efficiency and low fuel consumption of the internal conbustion engine has been mainly proceeding. To achieve these goals, the improvement of combustion process in Sl engine and the use of substitute energy are suggested. When the methanol blend fuel Is used, the combustion rate of the initial ignition is diminishing by high latent evaporation of methanol. But it attracts the attention because of the high octane number, and lean mixture peculiarity. Considering these facts, the gasoline-methanol blend fuel In engine operation has been used to compare and analyze the pressure development, rate of heat release, mass burned fraction, and combustion process. The results of experiment show the power increase, lean combustion and low harmful component of emission.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.397-398
• /
• 2006

In late years, from a trend for ecology of auto motive engine, low emission and low fuel consumption of engine become a social assignment. At the same time, the high output (high efficiency) is required, too. In order to meet those requirements, in comparison with conventional engines, lean A/F (Air fuel ratio) setting is becoming popular for the high performance engines of late years. Exhaust valve seat (sintered material) used in these engines has a problem in wear resistance, because it is exposed to the surroundings that is clean and a high temperature in comparison with the conventional engines. Therefore, wear mechanism with lean A/F of engine was analyzed.The exhaust valve seat (sintered material), that was superior in wear resistance, was developed.