• Journal of Korean Society for Atmospheric Environment
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• v.17 no.4
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• pp.313-319
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• 2001

The development of ozone SRP (Standard Reference Photometer) designated as a G-7 project by the Korean Ministry of Environment began 1997 and is now nearly completed. With the completion of the ozone SRP we will not only acquire a qualification to participate in the international ozone calibration system but also enhance calibration credibility of ozone similarly to that of other ambient air pollution monitors. As the ozone SRP uses highly cleaned blank air that can be distinguished from general ozone analyzer, it is possible to reduce errors associated with the determination of ozone via elongation of the absorption length as long as 1 meter In addition, gas chopping method hat been adopted to cut down interference of other substances and time drift. Furthermore, the system has also been modified to minimize the strayed ultra-violet noise along the light path. In this paper, a new method for uncertainty evaluation has been introduced, which is guided by the ISO (International Standard Organization) GUM (Guide to the Expression of Uncertainty in Measurement) through assessments of the uncertainty type B (that was impossible to estimate before) as well as the uncertainty type A (based on statistics).

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.1-8
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• 2007

The present research is based upon the numerical analysis of a car windshield in order to represent the optimum design guide to improve the overall defrosting performance of the system. First, the control factors that highly affect the defrosting performance of a car windshield are chosen and afterwards, the optimum variables of each control factor are extracted out to analyze its performance. The main control factors for this research are respectively, the air injection angle of a defroster nozzle, the height of a nozzle outlet, and the ratio of the width to the height of a nozzle outlet. For such case when the air inlet angle is relatively small, the flow near the vicinity of the inner face of a windshield tends to expand. As a consequence, the heat transfer rate through the windshield decreases. Also, the height of a nozzle outlet is recommended to maintain its size to minimum. However, when the ratio mentioned before is designed less than unity, the defrosting performance decreases.

• Journal of the Korean Society of Systems Engineering
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• v.9 no.1
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• pp.13-23
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• 2013

Operational Concept Descriptions or Document(OCD) shall be developed to understand stakeholder's desire for to-be-delivered system. But there is little study on methodology of OCD generation and many developers do not understand importance of OCD in Korea. According to Nicole Roberts' industry(18 U.S. companies and organizations) survey, only 30% of system development projects had OCD, too. Researchers and developers have opposing views regarding the generation of an OCD. Many researchers believe that the development and use of operational concepts at the start of large projects is essential. Alternatively, developers may view the OCD as a burden to the development process rather than an enabler due to the extensive documentation requirement. In this paper a couple of OCD guidelines were investigated to clarify how to build a CONOPS effectively and what to include. Finally, OCD for rotorcraft based Personal Air Vehicle System(PAVS) was developed as a case study. In the future, a template for generating OCD appropriate to Korean environment could be proposed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.3
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• pp.139-148
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• 2010

A centrifugal compressor for HFC-134a has been newly designed and developed. Flow analysis using commercial programs was used to evaluate performance and internal flow of the impeller, inlet guide vane and diffuser etc. The purpose of this study is to establish the design theory necessary to the development of HFC-134a centrifugal compressors and to supply basic data related to design by reviewing design values and experimental values through the performance test. The compressor for HFC-134a was also investigated experimentally to check compression performance. The calculated data coincide the test results of compressor. The data obtained in the present study are useful for design of HFC-134a centrifugal compressors.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.7
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• pp.675-682
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• 2009

Instead of direct driving like BLDC, the induction principle is adopted as a driving one for planar stage. The stage composed of four linear induction motors put in square type is activated by two-axial forces; low-frequency attractive force and thrust force of the linear induction motors. Here, the modified vector control whose new inputs are q-axis current and dc current biased to three phase current instead of d-axis current or flux current is applied extensively to overall motion of the stage. For the developed system, the precision step test and the constant velocity test are tried to guarantee its feasibility for TFT-LCD pattern inspection. However, to exclude a discontinuity due to phase shift and minimize a force ripple synchronized with the command frequency, the initial system is revised to the antagonistic structure over the full degree of freedom. Concretely describing, the porous air bearings guide an air-gapping of the stage up and down and a pair of liner induction motors instead of single motor are activated in the opposite direction each other. The performances of the above systems are compared from trapezoid tracking test and sinusoidal test.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.7
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• pp.363-370
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• 2013

HVAC&R systems are the most energy consuming building services, representing approximately half of the final energy use in the building sector. Despite their significant energy use, there is a lack of a consistent and homogeneous framework to efficiently guide research. This research is about the energy consumptions of HVAC&R systems, with the aim of establishing a common idea for the analysis of building energy efficiency. Our approach deals with the concept of an HVAC&R set that is composed of subsystems. A matrix combination evaluation is examined, and a total of 960 sets can be implemented in a large scale office building. A method as a tool for energy evaluations of HVAC&R systems, and HEET as a energy simulation program, were developed.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.9 no.1
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• pp.8-14
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• 2013

HVAC&R systems are the most energy consuming building services representing approximately half of the final energy use in the building sector. Despite their significant energy use, there is a lack of a consistent and homogeneous framework to efficiently guide research, mainly due to the complexity and variety of HVAC&R systems but also to insufficient rigour in their energy analysis. This research reviews energy consumption of HVAC&R systems with the aim of establishing a common idea for the analysis of energy efficiency. The paper focuses on energy flow of the HVAC&R which include air-conditioning, transport and heat generation system for low-energy buildings.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.1
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• pp.80-86
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• 2013

In an effort to decrease aviation accident worldwide, development of aviation safety management has been sought through aviation index and standardization, both by establishing SMS(Safety Management System). It also needs to be done in the domestic. both study on SMS which ICAO recommends and setting the top priority safety goal, each differently classified by nations. Accordingly, defining safety index and developing continuous monitoring approach. Aircraft accident reporting system in Air Force does not operate in a open approach method due to its uniqueness related to mission achievement. Therefore, limits of utilizing the recent worldwide aircraft data sharing and analyzing results to prevent accident is inevitable. This paper introduces an overview of ECCAIRS 5 which become the standard for the recent worldwide aviation safety reporting and data exchange system. Also using ECCAIRS 5, aircraft accident cases of the Air Force are classified such as accident type, year, month, occurrence category, and flight phase. The result of the study will provide a guide line for utilizing the civil system in prevention of future military aviation accidents.

• Transactions of the Society of Information Storage Systems
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• v.10 no.1
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• pp.1-6
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• 2014

Plasmonic lithography is the latest technique to overcome diffraction limit of previous optical lithography. In the plasmonic lithography, the nano gap between nano metal wave guide and photoresist should be in sub-wavelength region. SIL-based plasmonic lithography is the one of the solutions to maintain small air gap. However, the nano gap control is so sensitive that a little disturbance is able to have a large effect on the nano gap control. So, we analyzed the characteristics of disturbance, and then modified the previous controller to suppress the disturbance. We applied two peak filters which were fixed one and adaptively changeable one. We experimentally confirmed the improvement of the nano gap control, which reduced nano gap error by 30 %. The proposed control will improve the quality of lithography pattern.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.2
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• pp.69-74
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• 2015

In this work, we studied the shell and helically coiled tube heat exchangers. Shell and coil heat exchangers with different rate of water flow and plate heat exchanger with same capacity were tested for condensing conditions. We proposed design guide using modified Wilson plot method. We compared fouling characteristics between shell and coil heat exchanger and plate heat exchanger, when they were washed and were not washed. The shell and coil heat exchanger showed 120% of higher saturated fouling resistance value and 4% of better heat transfer ratio than the plate heat exchanger.