• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.8
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• pp.150-159
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• 1999

Exhaust system is composed of several parts. Among, them , design of muffler system strongly influences on engine efficiency and noise reduction. So , through comprehension of flow characteristics inside muffler is necessary . In this study , three-dimensional steady and unsteady compressible flow analysis was performed to understand the flow characteristics, pressure loss and amplitude variation of pulsating pressure. The computational grid generation was carried out using commercial preprocessor ICEM CFD/CAE. And the three-dimensional fluid motion inside the muffler was analyzed by STAR-CD, the computational fluid dynamics code. RNG k-$\varepsilon$ tubulence model was applied to consider the complexity of the geometry and fluid motion. The steady and unsteady flow field inside muffler such as velocity distribution, pulsating pressure and pressure loss was examined. In case of unsteady state analysis, velocity of inlet region was converted from measured pulsating pressure. Experimental measurement of pressure and temperature was carried out to provide the boundary and initial condition for computational study under three engine operating conditions. As a result of this study, we could identify the flow characteristics inside the muffler and obtain the pressure loss, amplitude variation of pulsating exhaust gas.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.2
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• pp.82-87
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• 2017

This paper presents performance improvement of CO gas sensor signal conditioner for early fire warning system. The warning system is based on the CO sensor and its advanced signal conditioning modules network that employ electochemical gas sensor. The electochemical has advantage of having a linear output and operating with a low consumption and fast response. This electrochemical gas sensor contains a gas membrane and three electrodes(working, counter, reference electrode) in contact with an electrolyte. To use a three-electrode sensor, a voltage has to be applied between the working and the reference electrode according to the specification of the sensor. In this paper, we designed these requirements that should be considered in temperature compensation algorithm and electrode measurement of CO sensor modules by using advanced signal conditioning method included 3-electrode. Simulation and experimental results show that signal conditioner of CO sensor module using 3-electrode have a advantage linearity, sensitivity and stability, fast response etc..

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.618-622
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• 2007

In the present study, the cooling and heating operation characteristics of a multi-heat pump have been experimentally investigated for the number of the indoor units(A, B, C) and the operating conditions. The heat pump was controlled by an inverter scroll compressor. The performance of the heat pump was measured by the multi-calorimeter of an air enthalpy method. Cooling and heating capacities and COPs were obtained at the cooling and heating temperature conditions and the setting temperatures of an indoor unit. With increasing the operation frequency of the compressor, the cooling and heating capacities of the heat pump increased linearly. The operation frequency region of the compressor was different as the combination of the indoor unit and the cooling/ heating condition.

• Journal of the Korean Chemical Society
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• v.5 no.1
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• pp.66-72
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• 1961

A small size Fischer-Tropsch Catalyst testing apparatus, designed for an operating pressure of 150 psig, was test fabricated from ordinary schedule 40 iron pipes. The operability of the apparatus was tested by charging the reactor tube with the Lurgi Fischer-Tropsch iron Catalyst and passing through it the water gas obtained by gasifying the Korean anthracite using steam and oxygen. With the kind of catalyst charged, the apparatus was proven to daily produce about 50c.c. of synthetic greasy product, water and water soluble compounds, by running at a temperature of $250^{\circ}C$ and at a space velocity of 180 volume of gas per volume of catalyst/hr. About 20 consecutive days of operation is claimed to be sufficient for gathering an enough amount of synthetic products for such ordinary tests as distillation analysis, density measurement, iodine value determination etc. This trial fabrication of apparatus may be the first case of its kind in Korea in that the work has been conducted out in much a pilot plant scheme rather than a routine laboratory way which depends on small glass ware apparatus.

• Membrane and Water Treatment
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• v.6 no.1
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• pp.27-42
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• 2015

In this study, poly (phenylene oxide) (PPO) and poysulfone (PSf) were sulfonated and aminated respectively. Both sulfonated poly (phenylene oxide) (SPPO) and aminated polysulfone (APSf) were characterized via the measurement of FT-IR, swelling degree, ion exchange capacity (IEC), and ion conductivity. Then the surfaces of these membranes were modified by surface fluorination using 2000 ppm $F_2$ gas against $N_2$ gas for 1 h at room temperature. The surface fluorinated SPPO and APSf membranes were characterized again to determine any differences between the pristine and fluorinated membranes. In total, 3 types of bi-polar membranes were prepared by varying the IEC of the APSf and having a fixed value for the IEC of the SPPO. The hypochlorite concentration generated by using the surface fluorinated membranes was dependent on the IEC of the APSf and ranged from 683 to 826 ppm, while there was a considerable improvement in the durability of the surface fluorinated membranes as they remained intact even after operating for 4 h.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.625-627
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• 2003

In this study, the Global Positioning System (GPS) data collected by the GPS receivers that were established as continuously operating reference stations by Central Weather Bureau and Industrial Technology Research Institute of Taiwan are utilized to investigate the impact of atmospheric water vapor on GPS positioning determination. The surface meteorological measurements that were concurrently acquired by instruments co-located with the GPS receivers include temperature, pressure and humidity data. To obtain the influence of the baseline length on the proposed impact study, four baselines are considered according to the locations of the permanent GPS sites. The length of the shorter baseline is about 66km, while the longer is about 118 km. The results from the studies associated with different baseline lengths and ellipsoid height were compared for the cases with and without a priori knowledge of surface meteorological measurements. The finding based on 66 days measurements is that the surface meteorological measurements have a significant impact on the positioning determination for the longer baseline case. The associated daily maximum differences are 1.1 cm and 1.4 cm for the baseline and ellipsoid height respectively. The corresponding biases are -8.1 mm in length and -7.3 mm in el lipsoid height.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.163-166
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• 2008

The helicopter flies at low level flight mode in its own operational range comparing to other aircraft categories. The low level flight means that the engine operates at variable atmospheric condition such as hot and cold temperature, snow, heavy rain, etc. Furthermore it may increase the entering possibility of engine foreign object damage particles like sand, dust, etc., i.e. this operating condition gives rise to damages of engine gas path components. An on-line condition monitoring program was developed by using SIMULINK, where measurement signals were simulated as an input module. The reliability and capability of the developed on-line condition monitoring were confirmed through application to a real helicopter engine health monitoring.

• Korean Journal of Optics and Photonics
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• v.12 no.5
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• pp.389-393
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• 2001

A wavemeter is realized using the fact that the coupling coefficient of a WDM coupler is a function of wavelength. Prototype devices with 1500 nm/1600 nm and 1510 nm/1550 nm WDM couplers are successfully fabricated and tested in the laboratory. The measurement resolutions are $\pm$0.27 nm over a wavelength range of 1515 nm~1576 nm for the device with 1500 nm/1600 nm WDM coupler and $\pm$0.103 nm over a wavelength range of 1520 nm~1543 nm for th4e device with 1510 nm/1550 nm WDM coupler. The dependence of operating characteristics on the input signal power is insignificant. However the temperature dependence is ~0.06 nm/$^{\circ}C$.

• International Journal of Computer Science & Network Security
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• v.22 no.12
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• pp.71-78
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• 2022

Electronic measuring devices have an important role in agricultural projects and in various fields. Electronic measuring devices play a vital role in controlling and saving soil information. They are designed to measure the temperature, acidity and moisture of the soil. In this paper, a new methodology to manage irrigation and soil fertility using an electronic system is proposed. This is designed to operate the electronic irrigation and adds inorganic fertilizers automatically. This paper also explains the concept of remote management and control of agricultural projects using electronic soil measurement devices. The proposed methodology is aimed at managing the electronic irrigation process, reading the moisture percentage, elements of soil and controlling the addition of inorganic fertilizers. The system also helps in sending alert messages to the user when an error occurs in measuring the percentage of soil moisture specified for crop and a warning message when change happens to the fertility of soil as many workers find difficulty in daily checking of soil and operating agricultural machines such as irrigation machine and soil fertilizing machine, especially in large projects.

• Journal of Astronomy and Space Sciences
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• v.35 no.3
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• pp.201-210
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• 2018

The characterization of detectors installed in space- and ground-based instruments is important to evaluate the system performance. We report the development of a detector performance test system for astronomical applications using the Andor iKon M CCD camera. The performance test system consists of a light source, monochromator, integrating sphere, and power meters. We adopted the Czerny-Tuner monochromator with three ruled gratings and one mirror, which covers a spectral range of 200-9,000 nm with a spectral resolution of ~1 nm in the visible region. Various detector characteristics, such as the quantum efficiency, sensitivity, and noise, can be measured in wide wavelength ranges from the visible to mid-infrared regions. We evaluated the Korea Astronomy and Space Science Institute (KASI) detector performance test system by using the performance verification of the Andor iKon-M CCD camera. The test procedure includes measurements of the conversion gain ($2.86e^-/ADU$), full well capacity ($130K\;e^-$), nonlinearity, and pixel defects. We also estimated the read noise, dark current, and quantum efficiency as a function of the temperature. The lowest measured read noise is $12e^-$. The dark current at 223 K was determined to be $7e^-/s/pix$ and its doubling temperature is $5.3^{\circ}C{\pm}0.2^{\circ}C$ at an activation energy of 0.6 eV. The maximum quantum efficiency at 223 K was estimated to be $93%{\pm}2%$. We proved that the quantum efficiency is sensitive to the operating temperature. It varies up to 5 % in the visible region, while the variation increases to 30 % in the near-infrared region. Based on the comparison of our results with the test report by the vendor, we conclude that our performance test results are consistent with those from the vendor considering the test environment. We also confirmed that the KASI detector performance test system is reliable and our measurement method and analysis are accurate.