• 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.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.4
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• pp.474-482
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• 2015

This study aims to investigate the patterns and incidence rates of morphological deformities during artificial fingerling production of blackhead seabream (BSB, Acanthopagrus schlegeli) juveniles by visual and soft X-ray observations of BSB juveniles (n=881) collected from four industrial hatcheries. Using both methods, we observed seven types of external deformity ($11.2{\pm}4.4%$) and eight types of skeletal deformity ($53.4{\pm}5.1%$). Lordosis occurred in all hatcheries with the highest frequency and the mean frequency was $13.1{\pm}4.4%$ (24.5% in total abnormal) by soft X-ray. Although they had a similar standard length (SL), juveniles with lordosis had a significantly lower condition factor and body weight than normally developed juveniles (P<0.05); normal distribution curves of histogram of body proportions, i.e., body height (BH)/head length (HL) and trunk (=SL-HL)/BH, indicated differences between normally developed juveniles and those with lordosis. In addition, 59% of juveniles with lordosis had vertebral curvature of less than $20^{\circ}$, generally at the $17^{th}$ vertebrae. It is expected that the above results will be used as basic data necessary for determining the cause of lordosis and for developing techniques to prevent this symptom in the fingering production industry of BSB juveniles.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.977-985
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• 2012

Performance optimization of a small engine intake port has been studied through computational and experimental approach. Port angle, flange area and port shape are very important design parameters affecting performance of an intake port. Especially, radius of curvature of intake port inner surface has major effect on the flow coefficient of an intake port. As increasing port angle and flange area, flow coefficient is increased because pressure distribution and pressure gradient in the intake port are improved. Even though computational results over-predict maximum 8% compared with experimental result, they describe the tendency of flow coefficient according to the design parameters. Optimized intake port shows about 4.5% improved flow performance.

• Journal of the Korea Concrete Institute
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• v.22 no.6
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• pp.825-832
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• 2010

Although a critical section reaches its flexural strength in reinforced concrete structures, the structure does not always fail because moment redistribution occurs during the formation of plastic hinges. Inelastic deformation in a plastic hinge region results in plastic rotation. A plastic hinge mainly depends on material characteristics. In this study, a plastic hinge length and plastic rotation are evaluated using the flexural curvature distribution which is derived from the material models given in Eurocode 2. The influence on plastic capacity the limit values of the material model used, that is, ultimate strain of concrete and steel and hardening ratio of steel(k), are investigated. As results, it is appeared that a large ultimate strain of concrete and steel is resulting in large plastic capactiy and also as a hardening ratio of steel increases, the plastic rotation increases significantly. Therefore, a careful attention would be paid to determine the limit values of material characteristics in the RC structures.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.150-150
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• 2010

Carbon nanotubes have drawn attention as one of the most promising emitter materials ever known not only due to their nanometer-scale radius of curvature at tip and extremely high aspect ratios but also due to their strong mechanical strength, excellent thermal conductivity, good chemical stability, etc. Some applications of CNTs as emitters, such as X-ray tubes and microwave amplifiers, require high current emission over a small emitter area. The field emission for high current density often damages CNT emitters by Joule heating, field evaporation, or electrostatic interaction. In order to endure the high current density emission, CNT emitters should be optimally fabricated in terms of material properties and morphological aspects: highly crystalline CNT materials, low gas emission during electron emission in vacuum, optimal emitter distribution density, optimal aspect ratio of emitters, uniform emitter height, strong emitter adhesion onto a substrate, etc. We attempted a novel approach to fabricate CNT emitters to meet some of requirements described above, including highly crystalline CNT materials, low gas emission, and strong emitter adhesion. In this study, CNT emitters were fabricated by filtrating an aqueous suspension of highly crystalline thin multiwalled CNTs (Hanwha Nanotech Inc.) through a metal mesh. The metal mesh served as a support and fixture frame of CNT emitters. When 5 ml of the CNT suspension was engaged in filtration through a 400 mesh, the CNT layers were formed to be as thick as the mesh at the mesh openings. The CNT emitter sample of $1{\times}1\;cm^2$ in size was characteristic of the turn-on electrical field of 2.7 V/${\mu}m$ and the current density of 14.5 mA at 5.8 V/${\mu}m$ without noticeable deterioration of emitters. This study seems to provide a novel fabrication route to simply produce small-size CNT emitters for high current emission with reliability.

• Journal of Korean Medicine Rehabilitation
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• v.23 no.4
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• pp.169-176
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• 2013

Objectives To investigate correlation between anthropometric data (neck circumference (NC), waist circumference (WC), body mass index (BMI), and body shape indexes) and radiological parameters of lumbosacrum. Methods The data of college students living in Seoul (n=24) were analyzed retrospectively. Anthropometric data of NC, WC, and BMI were measured. Lumbar spine X-ray film was taken to measure lumbar lordotic angle, Ferguson's angle. To evaluate body shape of participants, three indexes of neck-to-waist ratio (NWR), neck-to-height ratio (NHR), and waist-to-height ratio (WHR) were used. Anthropometric data's correlations with radiological parameters of lumbosacrum were investigated. Results Anthropometric data of NC, WC, and BMI had no significant correlation with radiological parameters of lumbosacrum. NWR had significant positive correlation with lumbar lordotic angle and Ferguson's angle. NHR and WHR had no significant correlation with radiological parameters of lumbosacrum. Conclusions The results suggest that NWR-related fat distribution in neck has significant correlation with radiological parameters of lumbosacrum regardless of obesity.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.462-467
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• 2007

From the research which it sees verification of the whole interpretation and local interpretation of the durability steel deck bridge a static test and it produces the test body which it sells with character and it executes smallness pul lek detailed interpretation it leads and the appropriate characteristic of smallness pul lek detailed interpretation and to sleep a nominal stress price and it compares it judges it does. The stress quality from each structure region which it follows in load stock location it analyzes and from the hazard which evaluates, the objective region the length rib and the bottom grater weld zone, the length rib and width rib connection department and the width rib with the father it divided. It investigated the stress distribution of the test body from these objective location, FEM interpretation it led and the conduct against each structure state tax it analyzed. General conduct the load stock location the floor plate is located in the center with interpretation price together symmetry characteristic to seem, it cannot be like that it cannot there is one actual test price. Like this reason the length rib and width rib connection actually production even production characteristic security it is a day when it is impossible with the curvature junction department which it blows, it follows in examination body deferment condition and form feed with the fact that it is visible a big difference even with error of some it becomes. Consequently for a data and the research which are more accurate it is judged with the fact that the effort which is prudent will be necessary.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.517-524
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• 2012

In this study, the effects of the inelastic shear behavior of beam-column joint and the vertical distribution of lateral load are evaluated considering higher modes on the response of RC OMRF using the pushover analysis. A structure used for the analysis was a 5-story structure located at site class SB and seismic design category C, which was designed in accordance with KBC2009. Bending moment-curvature relationship for beam and column was identified using fiber model. Also, bending moment-rotation relationship for beam-column joint was calculated using simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The results of pushover analysis showed that, although the rigid beam-column joint overestimated the stiffness and strength of the structure, the inelastic shear behavior of beam-column joint could be neglected in the process of structural design since the average response modification factor satisfied the criteria of KBC2009 for RC OMRF independent to inelastic behavior of joint.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.2 s.245
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• pp.120-127
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• 2006

The fatigue behavior of LIPCA was so sensitive to the manufacturing condition, the environmental factors and the change of the test apparatus. Therefore, we could be considering not only the relationship between the stroke range $({\Delta}h)$ and actuating frequency but also the relationship between the stroke range $({\Delta}h)$ and the total effective moment $(M^E)$. Thus, this study proposed the calculation method of the applying $M^E$ when the $({\Delta}h)$ of LIPCA was increased from 1.mm to 20mm. To estimate the relationship between the total effective moment $(M^E)$ and the Bernoulli-Euler bending moment (M) was reviewed. And the residual stress distribution of LIPCA and THUNDER using the CLT was evaluated. In conclusions, converting the $({\Delta}h)$ of LIPCA to the radius of curvature (p) and calculating the $(M^E)$, it was found that the p by the $M^E$ changed similarly as the $({\Delta}h)$. It was found that the $M^E$ was 2.2 times as the M. While CFRP and PZT of LIPCA, which had the superior compressive characteristic, had the compressive residual stress, GFRP was subject to the tensile residual stress. Since this reversed configuration between the compressive residuals stress and the tensile one was made, the requirement of the stroke range $({\Delta}h)$ increase was satisfied.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1557-1566
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• 2004

A flame extinction phenomenon is a typical unsteady process in combustion. Flame extinction is characterized by various physical phenomena, such as convection, diffusion, and the production of heat and mass. Flame extinction can be achieved by either increasing the strain rate or curvature, by diluting an inert gas or inhibitor, or by increasing the thermal or radiant energy loss. Though the extinction is an inherently transient process, steady and quasi-steady approaches have been used as useful tools for understanding the flame extinction phenomenon. Recently, unsteady characteristics of flames have been studied by many researchers, and various attempts have been made to understand unsteady flame behavior, by using various extinction processes. Representative parameters for describing flame, such as flame temperature, important species related to reactions, and chemi-luminescence of the flame have been used as criterions of flame extinction. In these works, verification of each parameter and establishing the proper criterions of the extinction has been very important. In this study, a time-dependent flame temperature and an OH radical concentration were measured using optical methods, and the instantaneous change of the flame luminosity was also measured using a high-speed ICCD (HICCD) camera. We compare the unsteady extinction points obtained by three different methods, and we discuss transient characteristics of maximum flame temperature and OH radical distribution near the extinction limit.