• Journal of Power System Engineering
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• v.20 no.2
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• pp.32-42
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• 2016

Under part load condition of spark-ignition engine, pumping loss had great effect on engine efficiency. To reduce pumping loss, the study designed spark-ignited engines to make direct spray of gasoline to combustion chamber. In spark-ignited direct-injection engines, ignition probability is important for successful combustion and flame propagation characteristics are also different from pre-mixed combustion. This study designed a visualization testing device to study ignition probability of spark-ignited direct-injection LPG fuel and combustion flame characteristics. This visualization device consists of combustion chamber, fuel supply system, air supply system, electronic control system and data acquisition system. Ambient pressure, ambient temperature and ambient air flow velocity are important parameters on ignition probability of LPG-air mixture and flame propagation characteristics, and the study also found that sprayed LPG fuel can be directly ignited by spark-plug under proper ambient conditions. To all successful cases of ignition, the study recorded flame propagation image in digital method through ICCD camera and its flame propagation characteristics were analyzed.

• Fisheries and Aquatic Sciences
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• v.2 no.2
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• pp.210-217
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• 1999

Chemical oxygen demand (COD), phytoplankton cell number and chlorophyll-a concentration (Chl-a), sediment mean grain size and ignition loss were studied to determine their temporal trends in the study area. Historical data of COD, cell number and Chl-a were gathered from the late 1960s or early 1980s to 1997, and trends in temporal domain were obtained from a simple regression. Sediments for grain size and ignition loss (as organic contents in sediments) were sampled from the Chokchon macrotidal flat bimonthly from September 1990 to November 1996, and were analyzed using the decomposition method of time series analysis. In general, the first three data showed increasing trends based on regression analysis. The trends of sediment grain size fluctuated in a neutral pathway while those of ignition loss yielded no increasing pattern. In contrast with the suggestions from Ahn and Choi (1998) who reported a coarsening variation in sediment grain size to be a cause of the directional and remarkable changes of macrofaunal communities in this area, we could not find such a corresponding variation pattern from our samples. In diagnosing eutrophication, a paradoxical phenomenon was encountered between the trends in water column (COD, cell number and Chl-a) and sediment (ignition loss) data. In this paper, we inferred the possible processes that produce the discrepancy. Some explanations and biological responses to eutrophication were predicted and discussed.

• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.3
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• pp.155-161
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• 2013

To reduce the personnel and material loss caused by fire, we propose the automatic fire extinguishing system based on the ignition point tracking using the flame detecter. This automatic fire extinguishing system is composed of the flame detecting system and the fire extinguishing system based on the water cannon. We study the method for the ignition point tracking and the automatic fire extinguishing using the water cannon and the flame detecter. The flame detecting system for the early fire detection and the ignition point tracking has to be satisfied the requirement of the detecting range and the flame detection time. So we study the signal process algorithm for an improvement of the flame detecting system.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.249-255
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• 2017

Using a magnetic separation process, pond ash generated in thermoelectric power plants was separated into magnetic materials and nonmagnetic materials in order to make it into a raw material of geopolymers and unburned carbon; screening characteristics according to the particle sizes and magnet strength levels of the pond ash were observed. Based on the results of magnetic separation into fine particle (0.15~0.84 mm) and rough particle (0.84~2.4 mm) pond ash using 3000 G magnets, the weight fraction and ignition loss of nonmagnetic materials were found to be higher than those of magnetic materials, regardless of the particle size. In the case of fine particle pond ash, when the magnet strength was increased from 3000 G to 10000 G, even those materials that were weakly magnetic were separated into magnetic materials, leading to drastic increases in the weight fraction of magnetic materials, such that the ignition loss accounted for 66.9 % (22.8 wt%) of the entire ignition loss of 32.6 wt%, despite of the low ignition loss. Based on the results of measurement of the compressive strength levels of geopolymers made of magnetic-separated rough particle pond ash, the compressive strength of geopolymers made of magnetic materials containing small amounts of unburned carbon was found to be 20 MPa.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.204.1-204.1
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• 2003

Rehmanniae Radix Preparata attributes good blood circulation and it has been used for the treatment of dizziness, men's sterility, excessive loss of blood and weakness. On the quality control of the commercial Rehmanniae Radix Preparata, quantitative determination of 5-hydroxymethyl-2-furaldehyde (5-HMF) using HPLC method has been conducted. Quantitative analysis of 5-HMF in Rehmanniae Radix Preparata showered average 0.121${\pm}$0.063% in 14 samples collected throughout the regions of Korea. Contents of loss on drying, residue on ignition and residue on acid insoluble ignition showered average 14.084${\pm}$2.804%, 3.415${\pm}$0.790% and 0.807${\pm}$0.474% respectively.

• Particle and aerosol research
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• v.10 no.4
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• pp.131-136
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• 2014

The importance of waste treatments is increasing because of the lack of resources and environmental problems resulted from economic growth policy. Especially, the pollutant dust which is one of the wastes should be treated considerately because it could cause secondary damages on the human health as well as environmental systems. Recently, massive amount of coal fly-ash is being produced in thermoelectric power plants. In this study, we compared two general methods used in estimating the amount of unburned carbon in fly-ashes to categorize the coal fly-ashes into several groups following their carbon contents. One is the "loss on ignition(KS L 5405) method" which estimates the change of mass after combustion, and it is generally used. Another one is measuring $CO_2$ gas content by burning solid carbon in the fly-ash, and it is called "$CO_2$ analysis method."

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.24-29
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• 1996

The purpose of this study is to propose new estimation method of unit cement content in hardened concrete. In general, the quantity of cement in hardened concrete is tested by hydrochlonic acid dissolving cement paste, however, hydrochloric acid dissolves sea shell contained in sea sand and lime stone in concrete. Therefore, the tested cement content is apt to estimate greater than actual cement content. The sodium gluconate solution dissolves only cement in concrete, it is hard to dissolve sea shell and lime stone as CaCo3. The effects of the quantity, concentration and temperature of sodium gluconate solution, the ignition temperature, the ignition loss of cement on the cement content and the percentage of dissolution of cement were investigated to establish a test method. From the results of these tests, the fundamental test method for cement content of hardened concrete by sodium gluconate is proposed.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.1
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• pp.24-34
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• 1985

The study of unsteady gas exchange processes in the inlet and exhaust systems of the single-cylinder 4-stroke cycle spark ignition engine is presented in this paper. The generalized method of characteristics including friction, heat transfer, change of flow area and entropy gradients was used for solving the equations defining the gas exchange process. The path line calculation was also conducted to allow for calculation of the gas composition and entropy change along the path lines, and of the variable specific heat due to the change of temperature and composition. As the result of the simulation, the properties at each point in the inlet and exhaust pipe, pressure and temperature in the cylinder, and charging efficiency were obtained. Pumping loss and residual gas fraction were also computed. The effect of engine speed, exhaust and inlet pipe length on the pumping loss and charging efficiency were studied showing that the results were in agreement with what has been known from experiments.

• Fire Science and Engineering
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• v.27 no.6
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• pp.50-56
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• 2013

The radiation effects on the auto-ignition and extinction characteristics of a non-premixed fuel-air counterflow field were numerically investigated. A detailed reaction mechanism of GRI-v3.0 was used for the calculation of chemical reactions and the optically-thin radiation model was adopted in the simulations. The flame-controlling continuation method was also used in the simulation to predict the auto-ignition point and extinction limits precisely. As a result, it was found that the maximum H radical concentration, $(Y_H)_{max}$, rather than the maximum temperature was suitable to understand the ignition and extinction behaviors. S-, C- and O-curves, which were well known from the previous theory, were identified by investigating the $(Y_H)_{max}$. The radiative heat loss fraction ($f_r$) and spatially-integrated heat release rate (IHRR) were introduced to grasp each extinction mechanism. It was also found that the $f_r$ was the highest at the radiative extinction limit. At the flame stretch extinction limit, the flame was extinguished due to the conductive heat loss which attributed to the high strain rate although the heat release rate was the highest. The radiation affected on the radiative extinction limit and auto-ignition point considerably, however the effect on the flame stretch extinction limit was negligible. A stable flame regime defined by the region between each extinction limit became wide with increasing the fuel temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.6
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• pp.21-30
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• 2005

Heat release analysis is a very importent method in understanding the combustion phenomena inside an engine cylinder. In this study, one-zone heat release analysis was used with the mesured cylinder pressures of an IDI(indirect injection), a HSDI(high speed direct injection) and a SI(spark ignition) engine. It has benefits of simple equation, fast speed, reliability. The object of the study is to compare the combustion characteristics among an IDI, a HSDI and SI engine. Result of analysis, the maximum heat release rate of a HSDI is higher than an IDI because of long ignition delay period. The heat release curve of a IDI is more linear than an HSDI, so the combustion characteristics of a IDI is similiar to that of an SI engine. There is a suggestion here that the combustion efficiency of a HSDI is highest of that of all engines because of the smallest heat transfer loss of all engines.