• Journal of Korean Society of Transportation
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• v.22 no.4 s.75
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• pp.159-173
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• 2004

This study utilizes the fuzzy logic and genetic algorithm to improve the existing incident detection models by addressing the problems associated with "crisp" thresholds and model transferability (applicability). The model's major components were designed to be a set of the fuzzy inference engines, and for the self-adaptation capability the genetic algorithm was introduced in optimization(or training) of the fuzzy membership functions. This approach is often called "the hybrid of fuzzy-genetic algorithm" The model performance was tested and found to be compatible with that of the existing well-recognized models in terms of performance measures such as detection rate, false alarm rate, and detection time. This study was not an effort for simple improvement of the model performance, but an experimental attempt to incorporate new characteristics essential for the incident detection model to be universally applicable for various roadway and traffic conditions. The study results prove that the initial objective of the study was satisfied, and suggest a direction that the future research work in this area must follow.

• Journal of Power System Engineering
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• v.12 no.4
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• pp.5-11
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• 2008

The RI gasoline engine haying a sub-chamber had a high cycle variation due to the difficulty of the residual gas scavenge in the sub-chamber. To solve this problem and improve the combustion performance of RI engine, we devised a method to inject directly CNG fuel into the sub-chamber. A DI diesel engine of single cylinder was converted into a RI-CNG engine and an electronic control unit for the engine was manufactured. In this study, the combustion characteristics of the RI-CNG engine were investigated with the injection timings and air excess ratios at the load conditions of 50% throttle open rate and 1700rpm. As the results from this study, the RI-CNG engine worked reliably under the condition of the ignitable lean limit of $\lambda=1.7$ by showing the $COV_{imep}$ below about 5%. And the highest thermal efficiency could be obtained in the injection timing that produced the high imep and the low $COV_{imep}$ at the same time. The CO emission concentration indicated very low values and the THC and $NO_x$ showed an opposite pattern. With a view to improving the thermal efficiency and reducing the harmful emissions, the proper control region of the ignition timing and the mixture ratio were nearly ATDC $20^{\circ}\sim50^{\circ}$ and $\lambda=1.4$ respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.5
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• pp.43-50
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• 2008

DLN-2.6 combustion tuning was carried out for the maintenance of GE 7FA+e gas turbine at Seo-Incheon combined cycle power plant. DLN-2.6 combustion system has the higher level of yellow plume and combustion vibration problem in the initial operating mode than that of the base mode($100{\sim}160MW$). The objectives of this study are to investigate the causes of yellow plume and combustion vibration problems at the starting mode and to suggest the best operating condition for the reliable working of the real combustors. By the analysis of tuning data, we could conclude that a yellow plume is caused by the rich mixture(${\phi}{\sim}1$) in a PM 1 nozzle at mode 3($20{\sim}30MW$). In addition, the combustion vibration($120{\sim}140Hz$) might be related to the cold flow characteristics of PM 3 nozzles at mode 6B($40{\sim}45MW$).

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.5
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• pp.51-59
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• 2008

DLN-2.6 combustion tuning was carried out for the maintenance of GE 7FA+e gas turbine at Seo-Incheon combined cycle power plant. DLN-2.6 combustion system has the higher level of yellow plume and combustion vibration problem in the initial operating mode than that of the base mode($100{\sim}160MW$). The objectives of this study are to investigate the causes of yellow plume and combustion vibration problems at the starting mode and to suggest the best operating condition for the reliable working of the real combustors. By the analysis of tuning data, we could conclude that a yellow plume is caused by the rich mixture(${\phi}{\sim}1$) in a PM 1 nozzle at mode 3($20{\sim}30MW$). In addition, the combustion vibration($120{\sim}140Hz$) might be related to the cold flow characteristics of PM 3 nozzles at mode 6B($40{\sim}45MW$).

• Applied Microscopy
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• v.38 no.2
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• pp.97-105
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• 2008

The fine structural modification of the granulocytes between the molt and intermolt period were investigated by the transmission electron microscopy. The granular hemocytes of the spider Araneus ventricosus were composed of three subtypes: eosinophilic granulocytes (EGs), basophilic granulocytes (BGs) and cyanocytes. Both of the EGs and BGs have electron dense granules within their cytoplasms, however the granules of BGs are larger than those of EGs. During the molt period, some of the EGs have fine structural modification in their cell organelles including formation of phagosomes as a result of active phagocytosis. However, the BGs have no phagosomes, but electron densities of the granules are changed to lower states than the intermolt period. The cyanocyte is the biggest hemocyte among the granulocytes. They contain numerous hemocyanin crystals in the cytoplasm with some electron-lucent vacuoles. During the molt period, some of the cyanocytes are changed to irregular shapes. High magnification electron micrographs reveal that the lattice sub-structure of the hemocyanin crystals are very similar to those of microtubules, and each tubule is composed of approximately 20 filaments with fine fibrillar structure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.849-855
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• 2017

The development of a staged combustion cycle engine with higher perfomance is essential to provide higher transport capability of space launch vehicles. The combustor head of engine has a cone-shaped head and its manifold of combustor has a very complicated structure. The head and manifold have been manufactured by casting or machining methode. Metal 3D printing technologies are recently known as one of promising methods to improve manufacturing process for them because they are possible to over come limitations of the two methods. In this paper, a selective laser sintering method is used to make test materials and their physical properties are studying by changing its operation parameters to establish the better processing conditions. It is found that the 3D printing method is acceptable to manufacturing the head or manifold of combustor for staged combustion cycle engine.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.63-64
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• 2012

A pyrotechnic actuated device (PAD) is a component that delivers high power in remote environments by combustion of a self-contained energy source. Historically, the design of these devices has been largely empirical and considered to be an art. In this study, an overview for developing an analytical model is introduced that efficiently evaluates performance of PAD. The model is integrated by three parts of different disciplines that are coupled in sequence with each other. First is the solid explosive burning to form product gas within an actuator and transport to an expansion chamber. Second is the insertion of initially tapered piston into a small hole by gas pressure in the chamber. Third is the shear cutting of the diaphragm from the piston to enable gas flow into the conduit. Some results of preliminary study for each of three parts are introduced in the presentation.

• Journal of the Korea Computer Graphics Society
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• v.27 no.4
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• pp.1-9
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• 2021

Segmenting the compartments of neurons, such as axons, dendrites, and cell bodies, is helpful in the analysis of neurological phenomena. Recently, there have been several studies to segment the compartments through deep learning. However, this approach has the potential to include errors in the results due to noise in data and differences between training data and actual data. Therefore, in order to use these for actual analysis, it is essential to proofread the results. The proofreading process requires a lot of effort and time because an expert must perform it manually. We propose an interactive neuron structure proofreading method that can more easily correct errors in the segmentation results of a deep learning. This method proofread the neuron structure based on the characteristics of the neuron with structural consistency, so that a high-accuracy proofreading result can be obtained with less interaction.

• Journal of Practical Engineering Education
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• v.15 no.1
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• pp.183-192
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• 2023

This study analyzes the performance of flipped learning, an offline class method conducted in a degree-linked work-learning parallel system. Training in the work-study parallel system, which is conducted as part of job competency improvement, has thoroughly adhered to the offline method, but in line with COVID-19, unlike before, it is changing in the direction of using the online method more actively. However, educational methods such as flipped learning are not new because the degree-linked operation is applied to the academic system and education method of universities and is practically the same form as general university education. Therefore, it is necessary to analyze the educational performance and complementary points of flipped learning, which has recently been expanded in the degree-linked work-study parallel system, considering the characteristics of this system, in which classes are held only on weekends. As a result of statistical analysis based on the survey, some of the outcomes of flipped learning have been confirmed, and in order to increase the performances, it is necessary to continuously seek out specific measures to encourage learning and expand communication between instructors and students.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.1
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• pp.132-137
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• 2003

This study was carried out to investigate removal character of nitrogen and phosphorus with injection time of acetic acid on SBR, which is one of the biological treatment process. Wastewater used in experiment period was swine wastewater with character, relatively lower organic material concentration than nitrogen concentration. In the experiment with injection time of acetic acid, run 1 wasn't injected acetic acid during the anoxic period, and run 2 was injected intermittently acetic acid during the anoxic period of 15 hours. And run 3 was injected intermittently during the anoxic period of 3hours from end of wastewater filling. And filing time of the wastewater was 20hour from run 1 to run 3. In the study, the highest removal efficiency of organic and nitrogen were obtained by the operating condition of Run 2(the ratio of mixing/aeration time : 16.5/5.5, injection time of acetic acid : 15hours) and T-P was obtained by the operation condition of Run 3(the ratio of mixing/aeration time : 16.5/5.5, injection time of acetic acid : 3hours),and removal efficiency of $BOD_5$, $COD_{Mn}$, $COD_{Cr}$, T-N and T-P in the treated water was 96.1%, 87.7%, 90.6%, 86.6% and 84.5%, respectively.