• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.3
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• pp.103-110
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• 2008

In this paper, an efficient butterfly structure for 8K/2K-Point Radix-4 FFT algorithm using CORDIC(coordinate rotation digital computer) is proposed. It is shown that CORDIC can be efficiently used in twiddle factor calculation of the Radix-4 FFT algorithm. The Verilog-HDL coding results for the proposed CORDIC butterfly structure show 36.9% cell area reduction comparison with those of the conventional multiplier butterfly structure. Furthermore, the 8K/2K-point Radix-4 pipeline structure using the proposed butterfly and delay commutators is compared with other conventional structures. Implementation coding results show 11.6% cell area reduction. Due to its efficient processing scheme, the proposed FFT structure can be widely used in large size of FFT like OFDM Modem.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.5
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• pp.155-164
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• 2020

This research used Analytic Hierarchy Process(AHP) to analyze the importance and priority of functional space and evaluation factors of each functional space of the military dining facility. Dining in the military is an important factor in restoring combat power and promoting morale. The military dining facility serves as a not only for meals, but also for watching TV, education and club activities. Workers working in dining facility spend most of their work hours in dining facility, perform tasks such as cooking, dishwashing, and leftover disposal, and take breaks. As such, the military dining facility is a space where various functions are performed, and space planning should take into account these various functions when planning the building of the dining facility. However, the criteria for defense and military facilities, which are the basis for planning the space of military dining facility, are calculated only by simply analyzing the standard floor plan to match the size of the person-to. Therefore, when there is space to be reduced in the total area, there are side effects such as leaving visible table space without consideration for priority or functional space, unseen office space, and adjusting the entire area through reduction of the lounge. Accordingly, based on the priority of the space that the staff of the military dining facility considers important, this research aims to analyze the characteristics of each functional space through classification according to its unique function. This can be an indicator that can be used as a basis for future revision of the building floor area standards of the defense and military facilities standards, and it can improve usability with an efficient space plan that takes into account the characteristics of the Korean military and the satisfaction of its workers. Furthermore, efficient use of the defense budget through rational building plans can contribute to budget reduction.

• CDE review
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• v.4 no.3
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• pp.26-31
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• 1998

Recent trend of popularity of CAE(Computer Aided Engineering) tools and its availability, partly contributed by significant price reduction of H/W and SW, makes us believe CAE has already established terra firma as de jure tools, enablint the design improvement in the manufacturing am. However, if your jobs are required to be working closely with engineers located in the front line of manufacturing site, CAE is observed far from popularity, still being regarded as exclusive tools for engineers holding advanced degrees. Conventional methodologies depending on knowledge that was accumulated thorough trial and errors, depending primarily on engineering tables and formulas or proprietary know-how, are preferred as the de factor standard under the roof of contemporary development shops. Samsung camera, having stared its business since early 、80, has accumulated enough technological strength to compete in the world market. As today's consumers demand more sophisticated featured-lighter weight, built-in multi zoom and miniature size fitting in the palm-from camera manufacturer, so should Samsung camera respond to ever-delicate consumer's needs with great flexibility. Consequently conventional designers, without sophisticated analytical tools, with encounter solving the critical design factors that have never been treated as seriousness-marginal safety factors induced by reduced size of parts. In the study, CAE results of boss and gears were demonstrated as examples, which confirms the facts that the simple analysis done by front line designers, can bring distinguishable effects on the potential improvements of design and on the consequential influences on the future design process-simulation before actual tooling and productions.

• Journal of Powder Materials
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• v.21 no.6
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• pp.441-446
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• 2014

In this study, we synthesize silica-core gold-satellite nanoparticles (SGNPs) for the surface-enhanced Raman scattering (SERS) based sensing applications. They consist of gold satellite nanoparticles (AuNPs) fixed on the silica core nanoparticles, which sizes of AuNPs can be tunned by varying the amount of reactants (growth solution and reducing agent). Their surface plasmon resonance (SPR) properties were characterized by using UV-vis spectroscopy, showing that the growth of AuNPs on silica cores leads to the light absorption in the longer wavelength region. Furthermore, the size increase of AuNPs exhibited the dramatic change in SERS activity due to the formation of hot spots. The optimized SGNPs showing enhancement factor ${\sim}3.8{\times}10^6$ exhibited a detection limit of rhodamine 6G (R6G) as low as $10^{-8}M$. These findings suggest the importance of size control of SGNPs and their SPR properties to develop highly efficient SERS sensors.

• Fire Science and Engineering
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• v.21 no.1 s.65
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• pp.51-59
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• 2007

The purpose of this study is analyzing the fire behavior according to the fire load for G underground shopping mall located in Daegu city. when predict fire behavior, fire load and ventilation coefficient are important factor who dominate fire temperature or fire continuance time. Therefore, size of unit room, opening size and inflammable investigated on the field. Fire load calculated using unit calorific value by each material of inflammable that investigate. And reduction model experimented fire load about 6 models with variable. Fire behavior analyzed by heat flows of inside space that temperature rise and temperature change by time of fire source.

• Applied Microscopy
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• v.46 no.2
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• pp.105-109
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• 2016

Palladium has been used as a catalyst not only in Suzuki and Heck cross coupling reaction in organic chemistry, but also in automobile industry for the reduction of vehicle exhausts. The catalytic activity of Pd nanoparticles depends strongly on their size and exposed crystalline facets. In this study, the single crystalline palladium nanocubes/nanorods were prepared in the presence of polyvinyl pyrrolidone (PVP) and potassium bromide (KBr) using the polyol method. Selected area diffraction pattern and high-resolution transmission electron microscopy (TEM) were performed by TEM. The result shows that the ratio of KBr/PVP is the key factor to determine whether the product is cubes or rods. The as-prepared Pd nanocubes were highly uniform in both size and shape. The ordered packing structures including monolayer and multilayer can be fabricated via the rate-controlled evaporation of solution solvent. The catalytic activity of these Pd nanocubes towards heck reaction of iodobenzene with acrylate or acrylic acid was found to be higher than that of Pd nanorods. We suspect it is caused by the difference of energy state while Pd nanocubes is {100} plane and nanorods is {111} plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.172-177
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• 2004

In this paper, DGS(Defected Ground Structure) is applied to multi-layer structure using LTCC(Low Temperature Co-fired Ceramics). Sprial DGS is adopted in order for size-reduction and higher quality factor, the multi-layer DGS has the same characteristics as the planar DGS. Multi-layer bandpass filter of new shape is confiured using two multi-layer spiral DGS and is designed with no via-hole for the simple process. 5.25 GHz Wireless LAN bandpass filter is designed and fabricated, the insertion loss of the filter is measured less than 1.5 dB, and the size is 2.0 mm${\times}$1.2 mm${\times}$1.1 mm(L${\times}$W${\times}$H).

• Journal of Astronomy and Space Sciences
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• v.34 no.4
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• pp.251-256
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• 2017

The electric coupling between the lithosphere and the ionosphere is examined. The electric field is considered as a timevarying irregular vertical Coulomb field presumably produced on the Earth's surface before an earthquake within its epicentral zone by some micro-processes in the lithosphere. It is shown that the Fourier component of this electric field with a frequency of 500 Hz and a horizontal scale-size of 100 km produces in the nighttime ionosphere of high and middle latitudes a transverse electric field with a magnitude of ~20 mV/m if the peak value of the amplitude of this Fourier component is just 30 V/m. The time-varying vertical Coulomb field with a frequency of 500 Hz penetrates from the ground into the ionosphere by a factor of ${\sim}7{\times}10^5$ more efficient than a time independent vertical electrostatic field of the same scale size. The transverse electric field with amplitude of 20 mV/m will cause perturbations in the nighttime F region electron density through heating the F region plasma resulting in a reduction of the downward plasma flux from the protonosphere and an excitation of acoustic gravity waves.

• The Journal of Fisheries Business Administration
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• v.34 no.1
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• pp.31-44
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• 2003

The purpose of this study is to investigate empirically interaction among the financing decision, investment decision, and profitability by using 41 fisheries corporations in Korea, and to suggest implications of the empirical results for government's financial policy for fisheries corporations. Sample period is 19 years from 1982 till 2000. This analysis method employs the two stage least squares(2SLS) estimation method. From the results of regression analysis by 2SLS estimation method, the adjusted $R^2$ values were high and the overall F values indicated significant. The empirical results of this study are as follows; (1) determinant factors of capital structure model for fisheries are profitability, firm-size, fisheries investment of total asset, and business risk. As pecking order theory explains, the higher is profitability the lower is debt ratio. The larger firm-size, the higher is debt ratio. The higher is fisheries investment of total asset and business risk, the higher is debt ratio. (2) determinant factors of investment model for fisheries are the change of sales, business risk, and debt ratio. These factors have positive relation to fisheries investment of total asset (3) determinant factors of profitability model for fisheries are fisheries investment of total asset and debt ratio. These factors have negative relation to profitability. On the basis of analysis results, on the government's financial policy for fisheries corporations, I suggests that with interest rate reduction, the government should lend more funds to solve the crisis in the financial structure of the fisheries firms

• Journal of ILASS-Korea
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• v.27 no.4
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• pp.173-180
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• 2022

Cooling fog is being used in various parts of society such as fine dust reduction, cleanliness, and temperature drop. Cooling fog has the advantage of low flow rate and ease of use compared to other spray systems. In the case of cooling fog, it was confirmed that the injection angle increased as the pressure increased and the nozzle diameter increased. In this study, the minimum injection angle was 33.61 degrees and the maximum injection angle was 107.38 degrees. It was confirmed that the larger the nozzle diameter and the smaller the pressure, the larger the droplet size. In addition, it was confirmed that the Sauter Mean Diameter (SMD) increased along the X and Y axis directions. It was confirmed that the size of the droplet decreases as it approaches the nozzle tip due to the characteristics of the nozzle design factor.