• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.167.1-167.1
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• 2011

Sustainable energy generation is becoming extremely imperative due to the expected limitations in current energy resources and to reduce pollution. Especially, because of its considerable energy potential, ocean wave energy has been investigated with regard to power generation. To develop large high power wave generator system, it is important to make a small scale proto type and to test that. Thus the objective of this research is to examine the characteristics of a mechanically excited generator system having small power capacity experimentally. The water reservoir (4 m length, 1.5 m width and 1.8 m depth) having a wave maker to make arbitrary height and period of the water wave was made. The proto type consists of three main parts; a buoy, rack-pinion base one-way mechanism, and a wave generator(Fig.1). The water wave is going up and down and the hexahedron buoy is following the wave. The rack gear attached to the buoy is also going up and down to roll the pinion connected to an electric generator then it produces electricity. The experiments were performed with several conditions of water waves, and the power outputs over 30 W could be measured for some conditions. In future works, to achieve higher performance for the proto type, the effects of primary parameters (buoy shape and mass, etc.) on the system efficiency will be identified.

• Journal of the Korean Society of Radiology
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• v.13 no.7
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• pp.941-946
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• 2019

Computed tomography (CT) has been increasing in frequency and indications for use in clinical diagnosis and treatment decisions. Multidetector CT has the advantage of shortening the inspection time and obtaining a high resolution image compared to a single detector CT, but has been pointed out the disadvantage of increasing the radiation exposure. In addition, when the low tube voltage is used to reduce the exposure dose in the CT, noise increases relatively. In the existing method, the method of finding the optimal image quality using the method of adjusting the parameters of the image reconstruction method is not a fundamental measure. In this study, we applied a double-tree complex wavelet algorithm and analyzed the results to maintain the normal signal and remove only noise. Experimental results show that the noise is reduced from 8.53 to 4.51 when using a complex oriented 2D method with 100kVp and 0.5sec rotation time. Through this study, it was possible to remove the noise and reduce the patient dose by using the optimal noise reduction algorithm. The results of this study can be used to reduce the exposure of patients due to the low dose of CT.

• Journal of Korean Society of Steel Construction
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• v.24 no.6
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• pp.743-751
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• 2012

This paper investigates an experimental behavior of circular columns and beam-columns made of HSB600 high strength steel as a fundamental study to enhance the applicability of HSB steel. The applicability of the current Standard such as KBC and Eurocode 3 is also evaluated. A total of six specimens are fabricated and tested. The main parameters are slenderness ratio(KLe/r = 12, 14, 40, 65), diameter-to-thickness ratio(D/t = 25, 40), and eccentricity ratio(e/D = 0, 0.5). It is drawn from the experiment that both the KBC and Eurocode 3 can be used to predict the strength of circular columns and beam-columns made of HSB600 high strength steel.

• International Journal of Automotive Technology
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• v.8 no.3
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• pp.269-274
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• 2007

A prior fundamental study was executed using a constant volume chamber (CVC) to improve the burning characteristics of lean pre-mixture by the injection of active radicals generated in the sub-chamber of the CVC. The Radical ignition (RI) technique shows remarkable progress in the burning velocity and combustible lean limit compared with the results of the spark ignition (SI) technique. The optimum design value of the sub-chamber geometry is near $0.11cm^{-1}$ for the ratio of the total area of the holes to the sub-chamber volume $(A_h/V_s)$. In this study, based on the former experimental results, the additional works have been performed to examine the effects of the geometry change in the number $(N_h)$, the total section area $(A_h)$, and diameter $(D_h)$ of the passage holes on the combustion characteristics in the CVC. Also ambient conditions such as the initial temperature and the initial pressure of the mixture were selected as experimental parameters and the effects of residual gas at the chamber on the combustion characteristics were investigated. As a result, the correlation between the passage hole number and overall passage hole area was grasped. The effects of the initial temperature were significant, but on the other hand, those of the initial pressure were weak. A more detailed analysis on the residual gas is required in the future.

• Analytical Science and Technology
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• v.10 no.5
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• pp.370-377
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• 1997

The several fundamental parameters on the solvent extraction of Co(II), Cu(II) and Zn(II) with dithizone were investigated. The value of $K_{a1}/K_p$ of dithizone(at $25^{\circ}C$) between an aqueous phase and a chloroform was found to be $4.72{\times}10^{-11}$. And the mole ratios of metal ion to dithizone in its metal complexes were determined by mole ratio method. The extractibilities(%) for metal-dithizone chelates were obtained from the extraction equilibria of metal-dithizone complexes between an aqueous phase and a chloroform as follows. Co(II) : 92.3% at pH 8.0 : Cu(II) : 97.1% at pH 4.0 and Zn(II) : 99.0% at pH 7.0. And also, in optimum experimental conditions the extraction constants of Co(II), Cu(II) and Zn(II) were examined.

• Korean Journal of Environmental Agriculture
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• v.11 no.1
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• pp.20-25
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• 1992

To understand the fundamental features of reservoir environment and its future aspects, a simple predictive model for water quality was attempted with the aid of data easily obtained, Based on the data from 12 reservoirs in Korea, application of the simple predictive model was successfully made by means of statistical methods and simple physical submodels. Significant information on th effects of retention time on primary production in a reservoir, longitudinal change in water quality affected by certain non-dimensional parameters were also obtained. The chlorophyll-a concentration can be predicted by the equation as ; chlorophyll-a=($395{\time}limiting$ nutrient concentration) - 1.090.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.1-16
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• 1999

Differential equations and its numerical solution program using Turbo-C were formulated to describe the radical distribution and average displacement amplitude of vibrating dehydrated contact lens(HEMA) driven by sinusoidal or rectangular pressure. The natural resonant frequency of the lens diaphram(thickness 0.08mm, diameter 14mm, curvature radius 8mm) was measured to be 5730 Hz from the extrapolation of frequency vs addedmass to the diaphram curve. The Young's modulus of the lens was measured to be $4{\times}10^9$ Pa with altering the original shape. The effect of parameters such as thickness, effective radius, damping coeff., amplitude of driving pressure on the vibration characteristics was illustrated by the computer simulation of the derived program. When the frequency of driving pressure coincides with the integral multiple of fundamental resonance frequency of the lens the wave pattern changes from arc to bell-shape along the radial position of the diaphram. If this happens to the contact lens on the cornea in vivo, it might create the feel of pull of the lens due to the increased rise of central part of the lens.

• CELLMED
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• v.5 no.1
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• pp.7.1-7.7
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• 2015

According to Ayurveda, an individual can be classified into any one of the seven constitutional types (Prakriti) depending on the dominance of one, two, or three Doshas. A 'Dosha' is representative of fundamental mechanisms that are responsible for homeostasis, and thus, to health. In the recent years, there have been several efforts to see whether certain physiological, haematological or biochemical parameters have any relationship with the constitutional types or not. The objective of the present study was to see if the results of autonomic function tests vary according to Prakriti of an individual. We conducted this study in clinically healthy volunteers of both the gender belonging to the age group of 17 to 35 years after obtaining their written consent. The Prakriti of these volunteers was assessed on the basis of a validated questionnaire and also by traditional method of interviewing. After confirming that the primary Dosha ascertained by both these methods matched, 106 volunteers were grouped into three on the basis of primary Dosha and were subjected to various autonomic function tests such as cold pressor test, standing-to-lying ratio, Valsalva ratio and pupillary responses such as pupil cycle time and pupil size measurement in light and dark. The results suggest that, the autonomic function tests in the healthy individuals may correlate linearly with the primary Dosha expressed in an individual. In particular, people with Kapha as the most dominant Dosha showed a tendency to have either a higher parasympathetic activity or a lower sympathetic activity with respect to their cardiovascular reactivity in comparison to the individuals with Pitta or Vata as the most dominant Dosha.

• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.265-269
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• 2006

Anti-Roll Tanks, also called Sloshing Tanks, is a rather common and sometimes an efficient method of limiting the roll angles. The important parameters, when considering using anti-roll tanks, are positioning, size, duct area, flow control device etc. Measurement by the PIV(Particle Image Velocimetry) was conducted to investigate the flow characteristics around control damper and inlet area of duct for three kind of inclined angle $(\alpha=0^*,\;10^*\;and\;20^*)$. Flow behaviors such as instantaneous and time-mean velocity vectors are investigated. Furthermore, to reveal boundaries between flowing and stagnant zones and to extract velocity profiles at any selected sections of the lower duct for passive anti-rolling tanks system.

• Structural Engineering and Mechanics
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• v.64 no.6
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• pp.765-781
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• 2017

The out-of-plane response of infill walls has recently gained a growing attention and has been recognised fundamental in the damage assessment of reinforced concrete and steel framed buildings subjected to seismic loads. The observation of damage after earthquakes highlighted that out-of-plane collapse of masonry infills may occur even during seismic events of low or moderate intensity, causing both casualty risks and unfavourable situations affecting the overall structural response. Even though studies concerning the out-of-plane behaviour of infills are not as many as those focused on the in-plane response, in the last decades, a substantial number of researches have been carried out on the out-of-plane behaviour of infills. In this study, the out-of-plane response is investigated considering different aspects. First, damages observed after past earthquakes are examined, with the aim of identifying the main parameters involved and the most critical configurations. Secondly, the response recorded in about 150 experimental tests is deeply examined, focusing on the influence of geometrical characteristics, boundary conditions, prior in-plane damage, presence of reinforcing elements and openings. Finally, different theoretical capacity models and code provisions are discussed and compared, giving specific attention to those based on the arching theory. The reliability of some of these models is herein tested with reference to experimental results. The comparison between analytically predicted and experimental values allows to appreciate the extent of approximation of such methods.