• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.67-76
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• 2024

Objectives: Direct reading instruments (DRIs) are widely used by industrial hygienists and other experts for preliminary survey and identifying source locations in many industrial fields. Photoionization detectors (PIDs), which are a form of hand-held portable DRIs, have been used for a variety of airborne vaporized chemicals, especially evaporated hydrocarbon solvents. The benefits of PIDs are high sensitivity between each chemical, competitive price, and portability. With the goal of increasing the accuracy of logged PID concentrations, previous studies have performed tests for the assessment of single chemical compounds, not mixtures. The purpose of this preliminary study was to measure mixtures with a PID and charcoal tube at the same time and compare the accuracy between them. Methods: A chamber test was implemented with different mixtures of hydrocarbon chemicals (acetone, isopropyl alcohol, toluene, m-xylene) and levels in the range of 14 to 864 ppm. Three PIDs and charcoal tubes were connected to the chamber and measured the chemical mixtures simultaneously. A comparison of accuracy and the PID group of concentrations with manufacture correction factor (M_CF) and field correction factor (F_CF) applied was performed. Results: The accuracy of the PID concentrations data-logged from the PID did not meet the accuracy criteria except for the mixture level B and C logged from PID No. 2, which was 18% of all tests for meeting accuracy criteria. The mean and standard deviation (SD) of concentration (ppm) of the charcoal tube followed by each mixtures' level were 10.37±0.26, 155.33±5.28, 300.80±11.65, and 774.93±22.65, respectively. When applying F_CF into the PID concentrations, the accuracy increased by nearly 82%. However, in the case of M_CF, none met the accuracy criterion. Between the PID there were differences of logged concentrations. Conclusions: In this preliminary study, the concentration of a logged PID with F_CF applied was a better way to increase accuracy compared to applying M_CF. We suggest that additional research is necessary to consider environmental factors such as temperature and humidity.

• Journal of Families and Better Life
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• v.24 no.1 s.79
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• pp.71-82
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• 2006

The purpose of this study was to develop a standardized scale to measure consumers' motivation to purchase based on a self-determination theory. A preliminary 27-item scale was developed through literature review, diary analysis, and FGI. A questionnaire survey was conducted among 1,000consumers on internet using the preliminary scale. Then a series of tests, such as test-retest, item analysis, item-to-total correlation, Cronbach's reliability coefficient, and factor analysis, were conducted using the survey data. The final scale with21 items was constructed in the end. The Purchase Motivation Scale for Consumers consisted of five factors: (1) external motivation, (2) introjected motivation, (3) identified motivation I: self-respect, (4) identified motivation II: pursuit of harmony, and (5) internal motivation.

• 한국연소학회:학술대회논문집
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• 1997.06a
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• pp.135-151
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• 1997

The preliminary design and performance test for determining dimensions of gas turbine combustor were investigated. The combustor design program was developed and applied to design our combustor. and detailed design for determining of swirler. dome and liner holes were performed experimentally. The swirler. which govern the combustion characteristics of combustor, was determined $40^{\circ}$ as swirl angle at first performance test. After second performance test the swirler was re-determined by 24 mm i.d.. 34 mm o.d., and swirl angle of $45^{\circ}$. The geometry of liner holes were determined by considering the flame stability and recirculation zone size. It was found that flame can be more easily stabilized by adjusting the swirier dimensions rather than liner holes. The geometry of swirler and liner holes were re-determined by final performance test with dilution holes. Also. the performance of combustor was evaluated by analysis of exhaust gases.

• Animal Systematics, Evolution and Diversity
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• v.29 no.1
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• pp.56-69
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• 2013

A preliminary list of the following four tephritoid families is provided including 30 Korean species, of which 12 are new to Korea: two Lonchaeidae, three Pallopteridae (two new to Korea), 17 Platystomatidae (two new to Korea), and eight Ulidiidae (all new to Korea). This list is mainly based on the insect collection at the Yonsei University Wonju Campus and on previous publications concerning these taxa. Although a full taxonomic revision for each family is required in the long term, this preliminary list will provide a useful starting point to further investigation of these families. For the other three tephritoid families known in Korea but not treated in the present study, 89 species of Tephritidae, 14 species of Pyrgotidae, and one species of the rare family Ctenostylidae have been reported previously. A total of 134 species in seven families are officially recognized for the Korean fauna of the superfamily Tephritoidea.

• Journal of the Korean Society of Combustion
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• v.19 no.4
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• pp.21-27
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• 2014

MGT (micro gas turbines) have been gaining particular attentions with a variety of commercial and military applications due to their advantages such as compact size, simple operability, easy maintenance, and low emissions. This study deals with development processes of an annular combustor applied to MGT. Preliminary design methodologies are used to size the main components of the combustor. Key design features such as liner temperatures and pressure losses are evaluated. Results show that the estimated liner temperatures are within acceptable range. Dominant factors for pressure losses are estimated to be air admission holes and burner swirlers.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.287-288
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• 2012

Radio-loud active galaxies have been found to exhibit a close connection to galactic mergers and host galaxy star-formation quenching. We present preliminary results of an optical spectroscopic investigation of the AKARI NEP field. We focus on the population of radio-loud AGN and use photometric and spectroscopic information to study both their star-formation and nuclear activity components. Preliminary results show that radio-AGN are associated with early type, massive galaxies with relatively old stellar populations.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.795-800
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• 2001

In this study, a program to design a multi-stage axial compressor is developed wi th mean-line analysis and vortex methods. In a preliminary design stage, a method. to design in a short time is needed and mean-line analysis is usually used for this purpose. Arbitrary pressure ratio and reaction can be assigned to generate overall geometry and several vortex methods are adopted to consider the radial distribution of velocity and reaction. The variation of performance, when we use free vortex, forced vortex, and exponential method, is compared and discussed.

• Journal of Families and Better Life
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• v.27 no.4
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• pp.127-139
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• 2009

The purpose of this study was to develop a standardized scale to measure consume's impulse purchasing in internet shopping mall. As internet shopping is expanding rapidly, the consumer's impulse purchasing in the internet shopping is also increased. A preliminary 26-item scale was developed through a literature review. 1230 consumers responded to an online survey using the preliminary scale. This research was made with the intention of not only supplying the academic data on the consumer's impulse purchasing but also understanding the consume's basic behavior patterns in internet shopping mall. Then A series of tests, such as test-retest, item-to-total correlation, Cronbach's reliability coefficient and factor analysis, were conducted using the survey data. The final scale with 20-items was constructed in the end. The consume's impulse purchasing in internet shopping mall Scale for Consumers consisted of 4 factors.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.3
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• pp.58-63
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• 2008

ICAO has recommended ADS-B implementation that is considered as next generation surveillance system to meet the air traffic capability and aviation safety. However, safety verification for the new ADS-B technology should be carried out in advance. FAA performed a preliminary hazard analysis for ADS-B equipped aircraft through Capstone program in Alaska in order to reduce aviation accidents. The present study deals with ADS-B concept, FAA Capstone program and PHA for ADS-B equipped aircraft. We expect that this paper will be a valuable material to assess ADS-B risk when it is applied to the domestic environment.

• The KSFM Journal of Fluid Machinery
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• v.4 no.1 s.10
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• pp.38-45
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• 2001

A commercial CFD code is used to compute the 3-D viscous flow field within the impeller of a centrifugal pump. Several preliminary numerical calculations are carried out to determine the influence of the parameters such as the grid systems, the numerical schemes, the turbulence models and the shape of the vaneless diffusers at the design flow rate. The results of the preliminary study are used for the calculation of the off-design flow conditions. The circumferentially averaged results such as the radial and tangential velocities, the exit flow angle, the slip factor, the static pressure and the total pressure are compared with the experimental data at the impeller exit to discuss the influence of the prescribed parameters.