• IE interfaces
• /
• v.20 no.3
• /
• pp.288-297
• /
• 2007

Success of semiconductor/LCD industry depends on its yield and quality of product. For the purpose, FDC (Fault Detection and Classification) system is used to diagnose fault state in main manufacturing processes by monitoring time series data collected by equipment sensors which represent various conditions of the equipment. The data set is segmented at the start and end of each product lot processing by a trigger event module. However, in practice, segmented sensor data usually have the features of data asynchronization such as different start points, end points, and data lengths. Due to the asynchronization problem, false alarm (type I error) and missed alarm (type II error) occur frequently. In this paper, we propose a robust process fault detection system by integrating a process event detection method and a similarity measuring method based on dynamic time warping algorithm. An experiment shows that the proposed system is able to recognize abnormal condition correctly under the asynchronous data situation.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.3
• /
• pp.92-98
• /
• 2003

An LPG engine for heavy-duty vehicles has been developed using liquid phase LPG injection (hereafter LPLi) system which has regarded as one of the next generation LPG fuel supply systems. In this wort to investigate the lean bum characteristics of heavy-duty LPLi engine, various injection timing (SOI, start of injection) and double ignition method were tested. The results showed that lean misfire limit of LPLi engine could be extended. by 0.2 $\lambda$ value, using the optimal SOI timing in LPLi system. Double ignition method test was carried out by installing the second spark plug and modified ignition circuit to ignite two spark plugs simultaneously. Double ignition resulted in the stable combustion under ultra lean bum condition, below $\lambda=1.7$, and extension of lean misfire limit compare to ordinary case. Therefore, LPLi engine with optimal SOI and double ignition method could be normally operated at around $\lambda=1.9$ and showed higher engine performance.

• Journal of Mechanical Science and Technology
• /
• v.15 no.11
• /
• pp.1533-1540
• /
• 2001

A high-temperature sodium stainless steel heat pipe was fabricated and its performance has been investigated. The working fluid was sodium and it was sealed inside a straight tube container made of stainless steel. The amount of sodium occupied approximately 20% of the total volume of the heat pipe and its weight was 65.7gram. The length of a stainless steel container is 1002mm and its outside diameter is 25.4mm. Performance tests were carried out in a room air condition under a free convective environment and the measured temperatures are presented. The start-up behavior of the heat pipe from a frozen state was investigated for various heat input values between 600W and 1205W. In steady state, axial temperature distributions of a heat pipe were measured and its heat transfer rates were estimated in the range of vapor temperature from 50$0^{\circ}C$ to 63$0^{\circ}C$. It is found that there are small temperature differences in the vapor core along the axial direction of a sodium heat pipe for the high operating temperatures. But for the range of low operating temperatures there are large temperature drops along the vapor core region of a sodium heat pipe, because a small vapor pressure drop makes a large temperature drop. The transition temperature was reached more rapidly in the cases of high heat input rate for the sodium heat pipe.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2910-2915
• /
• 2008

This paper was investigated the behaviors of the engine and combustion phenomena for various LPG compositions in the semi-return type system, which is not recircurated to LPG tank through furl rail, applied LPi engine during a cold idle condition and including a cold start of the engine. Cyclic HC and NOx emissions were measured at exhaust port to examine their formation mechanical and reduction mechanical with fast response gas analyzers. Various ignition timing is experimented to study the characteristics of combustion phenomena, HC/NOx emissions during fast idle. Also, this study was investigated start delay time, cylinder pressure, HC/NOx emissions, Mass Fraction Burned, starting time to evaluate performance of transient cold startability. Compared to the return type system, the semi-return type system have advantages in point of production cost and equivalent performance of engine starting time and pressure settling time.

• Journal of the Korean Society of Combustion
• /
• v.19 no.3
• /
• pp.44-52
• /
• 2014

Solid oxide fuel cell(SOFC) makes electric power using hydrogen or reformed from methane and emits high temperature products that contain flammable species like hydrogen, carbon monoxide and methane which varies with operation condition. SOFC/gas turbine integrated system which uses thermal and chemical energy of the discharges is more efficient than SOFC itself. Burning character of the SOFC products will affect the efficiency and stability of the system. Experiments were conducted to know the characteristics of the flame for two typical composition of SOFC products, i.e. start-up and steady state composition. When coflowing air temperature was higher than $600^{\circ}C$, auto-ignitin occurred for both fuels. Though start-up fuel has higher contents of hydrogen, it makes longer flame than steady state composition. It was inferred that the amount of oxidizer necessary to burn makes this phenomenon. Steady state composition fuel was unstable since it contains lots of water. Nozzle that had 6 holes, distance between each hole was 16.7 times of hole diameter, improved the stability of the flame.

• Journal of the Korean Society of Physical Medicine
• /
• v.18 no.3
• /
• pp.47-53
• /
• 2023

PURPOSE: A visual feedback method was proposed to induce brain stimulation in a stroke patient, and among them, there was a treatment using a mirror. On the other hand, mirror therapy focuses only on the functional changes in body movements, and analysis of neurophysiological mechanisms of brain activity is lacking. In addition, studies on evaluating the activity and response generated in specific brain regions during visual feedback training using mirrors are insufficient. METHODS: Fifteen healthy adults (male: 10, female: 5, Years: 23.33 ± 1.23), who were right-handed were recruited. By attaching the C3, Cz, and C4 channels in the sensorimotor cortex using an electroencephalogram, training was performed under the conditions without mirror-based visual feedback (No-condition) and with visual feedback (Tasks-condition). At this time, the immediate activity of the mu-rhythm in response to training was separated and evaluated. RESULTS: The tasks-condition of C3, Cz, and C4 channels activated the relative mu-rhythm rather than the no-condition, and all showed significant differences (p < .05). In addition, in all channels at the start time, the tasks-condition was more active than the no-condition (p < .05). The activity of the cortical response was higher in the tasks-condition than in the no-condition (p < .05). CONCLUSION: The mu-rhythm activity can be evaluated objectively when visual feedback using a mirror is applied to healthy subjects, and a basic analysis protocol is proposed.

• Journal of Wetlands Research
• /
• v.9 no.1
• /
• pp.123-131
• /
• 2007

Effect of nitrogen-load condition on hydrogen ($H_2$) production and bacterial community in a continuous anaerobic hydrogen fermentation were investigated. The slight $H_2$ production on extremely low nitrogen-load condition (C/N ratio: 180) at the start-up period. The highest $H_2$ production was obtained when the C/N ratio was 36, the $H_2$ production yield ($mol-H_2/mol-glucose$) reached to 1.7, and it was indicated that Clostridium pasteurianum mainly contributed to the $H_2$ production. The $H_2$ production was decreased on both the lower (C/N: 72) and higher (C/N: 18) nitrogen-load conditions. The excess nitrogen-load was not always suitable for the hydrogen production. The fluctuation of $H_2$ production seemed to be caused by a change in the bacterial community according to the nitrogen-load condition, while a recovery of $H_2$ productivity was possible by a control of nitrogen-load condition through the bacterial community change. When the nitrogen-load condition was not suitable for hydrogen production, the lactic acid concentration was increased and also lactic acid bacteria were definitely detected, which suggested that the competition between hydrogen fermentator and lactic acid producer was occurred. These results demonstrated that the nitrogen-load condition affect on the $H_2$ productivity through the change of bacterial community in anaerobic hydrogen fermentation.

• Journal of Environmental Science International
• /
• v.22 no.11
• /
• pp.1421-1431
• /
• 2013

This study was conducted for clarifying distribution and characteristics of marshy Ericaceae plants on Mt. Changbai in China. The marshy Ericaceae plants in wetland of Mt. Changbai were investigated on about 1400 m altitude. This region is various developmental wetlands and vegetation mixture of needle-leaf trees and broad-leaf trees. This region also is start point of the coniferous forest zone in Mt. Changbai. As results of these researches, L. palustre var. diversipilosum and L. palustre var. decumbens populations were investigated in Larix olgensis var. amurensis community. R. lapponicum subsp. parvifolium var. parvifolium community appeared as a typical community. Environmental conditions of L. palustre var. diversipilosum and L. palustre var. decumbens populations' habitats are more soil humidity and shade condition. R. lapponicum subsp. parvifolium var. parvifolium community habitat, however, has more deposits and humidity condition. Therefore when the plants were cultivated, we should recognize the growth condition such as maintenance of humidity and control deposits. The flora of marshy Ericaceae species habitats was investigated as 28 families, 49 genera, 45 species, 14 variety, 1 forma, 1 sub-species, and total 61 taxa.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.8 no.4
• /
• pp.26-33
• /
• 2000

In-cylinde flow and mixture formation are key contributors to both idle stability and combustion stability at part load condition in SI engine. The real time measurements of air-fuel ration and in- cylinder residual gas fraction are particularly important to obtain a better understanding of the mechanisms for combustion and emissions especially during cold start and throttle transient condition. This paper reports the cycle resolved measurements of residual gas fraction and equivalence ration near speak plug with value timing change and their effects on combustion characteristics at part load. The results showed that the effect of intake value opening on the residual gas fraction was smaller than that of exhaust valve closing because of the decreases of exhaust gas reverse flow from exhaust port. The variation of equivalence ratio near spark plug increased with the increase of value overlap and it closely related with heat release rate and combustion stability

• Journal of KSNVE
• /
• v.11 no.3
• /
• pp.461-470
• /
• 2001

A friction-type clutch system sometimes generates spick-slip vibration during engagement, which disturbs smooth start of a car and makes a passenger uncomfortable. In this study, the spick-slip vibration in four types of friction couples was investigated at two different engagement conditions respectively of which the amount of slip time and clutch travel was varied. Results are found as follows. First, the vibration increased at the condition of small engine torque and large torque fluctuations due to higher harmonics of engine speed. Second, the friction couple without a pre-damper has advantages of reducing the vibration. This study also suggested an evaluation method of vehicle vibration in the view point of human perception by using the frequency weighting of ISO2631-1.