• Journal of the Korea Concrete Institute
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• v.20 no.3
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• pp.405-412
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• 2008

Six alkali-activated (AA) concrete mixes were tested to explore the significance and limitations of developing an environmental friendly concrete. Ground granulated blast-furnace slag and powder typed sodium silicate were selected as source material and an alkaline activator, respectively. The main parameter investigated was the replacement level of lightweight fine aggregate to the natural sand. Workability and mechanical properties of lightweight AA concrete were measured: the variation of slump with time, the rate of compressive strength development, the splitting tensile strength, the moduli of rupture and elasticity, the stress-strain relationship, the bond resistance and shrinkage strain. Test results showed that the compressive strength of lightweight AA concrete sharply decreased when the replacement level of lightweight fine aggregate exceeded 30%. In particular, the increase in the discontinuous grading of lightweight aggregate resulted in the deterioration of the mechanical properties of concrete tested. The measured properties of lightweight AA concrete were also compared, wherever possible, with the results obtained from the design equations specified in ACI 318-05 or EC 2, depending on the relevance, and the results predicted from the empirical equations proposed by Slate et al. for lightweight ordinary Portland cement concrete. The stress-strain curves of different concrete were compared with predictions obtained from the mathematical model proposed by Tasnimi. The measured mechanical properties of lightweight AA concrete generally showed little agreement with the predictions obtained from these equations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.163-172
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• 2011

The CFTA girder developed is a concrete filled steel tubular system with arched shape and external post-tensioning (PT) tendons which control the initial camber and the bending stress of the girder. In the present study the effects of the PT tendons on the dynamic behavior of the girder subjected to a moving vehicle load are numerically investigated. Various levels for the tendon quantity and the tendon forces are considered, using the existing FE model of the girder. The vehicle considered is a DB-24 truck and is modeled with two tracks-three axles. Equivalent-load pulse time histories are applied to each node to simulate the moving vehicle, depending on the time of arrival and the discretization. The vehicle speeds are varied from 40 km/hr to 100 km/hr with increment of 20 km/hr. The analysis results show that the tendon forces do not produce any influences on the dynamic responses of the girder. However the dymamic deflection of the girder increases when a smaller amount of tendons is used. The Dynamic Amplification Factors (DAF) are evaluated based on the static and dynamic responses. Much lower values of the DAF are obtained, even no tendons applied, than those provided by the design criteria of the AASHTO LRFD and the Korea Highway Standard Specification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.6
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• pp.1453-1463
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• 1994

The SCS Curve Number(CN) method has become widely accepted as a procedure of estimating stormflow volumes for design and natural events in small watersheds. The applicability of this method for calculating the flushing time was evaluated as compared with the net volume transport(NVT) method in Masan Bay, Korea. It is shown that the flushing time using the CN method ranged from 10.9 to 15.3 days under the well mixed condition, that the time using the NVT method was 13.9 days averaged over 6 days of field data. These results were revealed that two methods calculated the approximate times as shown above. The relationships between the run-off, Qr, and the flushing time, t, are expressed as the following forms. $t_1=228.79Q_r^{-0.9996}$ in case of well mixed condition, (1) $t_2=131.06Q_r^{-1.0}$ in case of two layered model. (2) Those empirical expressions are represented that the relationships between Q and t are nonlinear as those as Bumpus obtained in Boston Inner Harbour. Therefore, the CN method will permit calculation of the flushing time for any given bay to be unexpected as water balance under the condition of short-time (0.5 day) data, instead of NVT method based on the long-time (at least 3 days over) data.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.7 no.2
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• pp.52-59
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• 2008

The objective of this study is to develop an automatic object changer unit to improve processing problems existed in the conventional horizontal machining center. To achieve this goal, this study designed a horizontal transfer as the second project continued to the first project that designed a upward and downward traverse unit. A horizontal traverse unit shows a symmetric structure and consists of frame, which consists of four unit tools, motor and reducer, which are fixed at a frame, operation unit with pinions, first traverse unit, and second traverse unit. Constraint conditions based on the operation mechanism with these elements were configured and obtained following results after modeling a model for a traverse motor. In the kinematic expression of sliding motion with one degree of freedom, the sliding motion is constrained. Also, the rack 3 installed at a frame is used to configure possible kinematic constraint conditions of the rack 2 according to the rolling motion of the pinion 2 in the first traverse unit. In addition, the moment of inertia that is a type of kinetic energy in a converted horizontal traverse unit in the side of the reducer can be applied to introduce the moment of inertia of a converted horizontal traverse unit in the side of the reducer by using the sum of kinetic energy in the rack and pinion, which is a part of the horizontal traverse unit. Also, the equation of motion of the converted upward and downward traverse unit in the side of the motor using the equation of motion of the motor. Furthermore, the horizontal traverse unit predetermines the mass of the first and second traverse unit and applied load including the radius and reduction ratio of the pitch circle in the pinion 1 and applied load to the rack 2. Then, a proper motor can be determined using several parameters in the upward and downward traverse unit in order to verify such predetermined specifications. In future studies later this study, a simulation that verifies the results of the previous two stages of studies using a finite element method.

• Korean Journal of Hospice Care
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• v.2 no.1
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• pp.21-40
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• 2002

Cancer is the second leading cause of the death in Korea. Family caregivers of dying patients manifest many psychological and physical symptoms of stress, and they often seek for informational support from health care providers. Unfortunately, however, few systematic studies identify the actual effect of such support on family caregivers. This study, thus, intends to evaluate the effect of informational support for hospice care. One group pretest-posttest design was used, employing the stress-coping model by Cohen and Wills as a conceptual framework. This research was conducted from July 1 to November 15, 1998, initially with 32 subjects sampled from hemato-oncology department of two general hospitals in Seoul, but reduced to 18 at the end due to the untimely death of patients or caregiver's refusal during the course of study. Informational supports were programmed to provide the family caregivers with 8 times of education and counseling as well as 24-hour hot-line for 4 weeks. A booklet that explains the various problems of hospice care was also prepared and distributed to all subjects. Data were collected by using self-report questionnaires and reviewing medical records. The tools used in this study were based on the Weinert's PRQ-II(scale of perceived social support), Spielberger's state anxiety inventory, and CES-D. Also included in the data collection were the general characteristics of family caregivers and patients, and the pain intensity and the performance status of patients. The data were analyzed with descriptive statistics, Wilcoxon sign rank test and paired t-test using SPSSWIN program. The results of the study were as follows: 1.The perceived social support of family caregivers was not significantly increased with informational support for hospice care(t=1.64, one tailed p=.060). 2.The anxiety of family caregivers was significantly reduced following informational support for hospice care(t=3.48, one tailed p=.002). 3.The depression of family caregivers was significantly reduced following informational support for hospice care(t=-2.18, one tailed=.022). 4.The pain intensity of patients with terminal cancer was significantly reduced following informational support for hospice care(t=-2.41, two tailed p=.027). The results suggest that the informational support provided to family caregivers of patients with terminal cancer reduced not only their anxiety and depression but also the pain intensity of patients. Further study is necessary to consolidate the conceptual framework of this study with expanded number of subjects. Nevertheless, it was certain that the informational support program for hospice care was very helpful to both caregivers and patients. Thus, the informational support program is strongly recommended for the hospitals which have no hospice unit yet.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.7
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• pp.37-47
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• 2011

Real picture like high quality computer graphic is widely used in various fields and shader processor, a key part of a graphic processor, has been advanced to programmable unified shader. However, The existing graphic processors have been optimized to commercial algorithms, so development of an algorithm which is not based on it requires an independent shader processor. In this paper, we have designed and implemented a control unit to support high quality 3 dimensional computer graphic image on programmable integrated shader processor. We have done evaluation through functional level simulation of designed control unit. Hardware resource usage rate are measured by implementing directly on FPGA Virtex-4 and execution speed are verified by applying ASIC library. the result of an evaluation shows that the control unit has the commands more about 1.5 times compared to the other shader processors that is a behavior similar to the control unit and with a number of processing units used in a shader processor, compared with the other processors, overall performance of the control unit is improved about 3.1 GFLOPS.

• Journal of Digital Convergence
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• v.15 no.8
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• pp.333-340
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• 2017

Timelapse is an imaging technique that captures motion at regular intervals and then projects it at normal speed. We looked at Timelapse advertising images of global brands and presented a model for analyzing components and expression methods of Timelapse, a new image technique. In previous research, literature research, Internet data survey, and YouTube data were investigated. Continuous photography has been developed as an imaging technique, and we have examined the current production status applied to domestic and foreign documentary, domestic and foreign drama, film, and advertisement. In 2015-2016, I will analyze the techniques of iPhones (2016), Ralph Lauren Polo Ads (2015), and Canon EOS (2013) videos that use Timelapse techniques in their recent advertisements. The results show that the Timelapse component is a static element, the static motif is mainly an artificial structure, the place is outdoor, the color is taken at a time showing the characteristics of the place, and the layout is all centered. The dynamic motif is a moving object. The dynamic line consists of a story based on the object. The time is about 11-15 seconds, the longest is about 1 minute and 30 seconds, and the editing is mainly focused on the product with the brand logo emphasized. In conclusion, it is the role of the image to pay attention to the advertisement and catch the eye. In order to motivate the buyer's mind, it is necessary to direct and edit such as Timelapse, which stimulates the emotions inherent in the mind and stimulates the non-verbal symbols. Future research is likely to reveal various attempts at temporal editing of images.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.1
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• pp.17-29
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• 2003

This paper preliminarily investigates the effectiveness of various control systems, such as passive, active, semiactive and hybrid control, for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. This benchm.0.00000ark problem considers the cable-stayed bridge that is scheduled for completion in Missouri, USA In 2003. Seismic considerations were strongly considered in the design of this bridge due to location of the bridge and its critical role as a principal crossing of the Mississippi River. Based on detailed drawings of this cable-stayed bridge, a three-dimensional linearized evaluation model has been developed to represent the complex behavior of the bridge. A set of eighteen evaluation criteria has been developed to evaluate the capability of each control system. In this study, four passive control systems, one active control system, two semiactive control systems and three hybrid control systems are considered. Numerical simulation results show that all the control systems are effective in reducing the responses of the benchmark cable-stayed bridge under the historical earthquakes. To get good performance, however, the passive control systems need quite large control forces compared to other control systems. The simulation results also demonstrate that the passive, semiactive and hybrid control systems are robust to the stiffness uncertainty of the structure. Therefore, the semiactive and hybrid control systems are more appropriate in real applications for full-scale civil infrastructures.

• Journal of Korean Society of Steel Construction
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• v.27 no.2
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• pp.243-250
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• 2015

An extended end-plate connection displays different behavioral properties and energy dissipation capacity based on the thickness and length of the end-plate comprising the connection in the form of a beam-to-column moment connection, the number and diameter of the high strength bolt, the gauge distance of the high strength bolt, and the size and length of the welds. Such extended end-plate is applied to beam-to-column connections in various geometric forms in the US and European regions. Currently in Korea, however, the extended end-plate beam-to-column connection is not actively applied due to the lack of proper design formulas, the evaluation of the energy dissipation capacity, and the provision of construction guidelines. Accordingly, this study was conducted to provide the basic data for the proposal of a prediction model of energy dissipation capacity by evaluating the energy dissipation capacity of unstiffened extended end-plate connections with relatively thin end plate thicknesses. To achieve this, a three-dimensional nonlinear finite element analysis has been conducted on unstiffened extended end-plate connections, with the thickness of the end plate as the set variable.

• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.69-75
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• 2014

Rock fall protection system installed against rock slope is one of the most conventional way to protect nearby infra structures. Despite of wide application of typical rectangular nets, virtually installed to protect rock slope face, several problems have also been pointed out up to date. Rectangular draped nets are vulnerable to a sudden external shock such as rock fall, because it doesn't have any systematical buffers or shock absorbers. Furthermore, it has been widely recognized from the some cases of rock fall accident in Korea that rock fall protection nets cause wide range of failure in the rock slope faces due to insufficient pullout bearing capacity of fixing parts. Therefore, in this study, we tried to make a consideration about the problems of existing standard rock fall protection nets in Korea, and develop a new type of hexagonal net with a shock absorber based on design rock fall energy. In this paper, laboratory and full scale test procedure is described to analysis the performance of newly developed hexagonal rock fall net, and the key results are presented and discussed.