• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.663-672
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• 2014

Recently, modular structural systems have been applicable to building construction since they can significantly reduce building construction time. They consists of several unit modular frames of which each beam-column joint employs an access hole for connecting unit modular frames. Their structural design is usually carried out under the assumption that their load-carrying mechanism is similar to that of a traditional steel moment-resisting system. In order to obtain the validation of this assumption, the cyclic characteristics of beam-column joints in a unit modular frame should be investigate. This study carried out finite element analyses(FEM) of unit modular frames to investigate the cyclic behavior of beam-column joints with the structural influence of access holes. Analysis results show that the unit modular frames present stable cyclic response with large deformation capacities and their joints are classified into partial moment connections. Also, this study develops a simple spring model for earthquake nonlinear analyses and suggests the Ramberg-Osgood hysteretic rule to capture the cyclic response of unit modular frames.

• Journal of the Korean Society of Costume
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• v.57 no.8
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• pp.37-47
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• 2007

This study is considered about the fabrics of the tomb of King Muryeong at the Baekje(百濟) Period. First, there were silk fabrics such as compound woven silk(錦), twill damask(綾), complex gause(羅) and plain weaved silk(平絹). All of compound woven silk(錦) are the warp-faced compound tabby(經錦) of plain weave and the density is various from high to low one. The twill damask(綾) was a variation of twill damask weaved with a six strand warp thread. The complex gause(羅) made patterns as a set of 2 strand, 4 strand, 6 strand and 8 strand warp threads are weaved alternately with the weft. There were three kinds of plain weaved silk(平絹). The first was weaved densely without space between strands. The second was weaved with a small space between strands. And the third was weaved with a two strand warp thread, having a space between the threads. On the other hand, several pieces of well preserved ramie cloth were excavated. Of the, the densest one has the density of 125 strand/inch for the warp and the weft. In addition, strings made of flax thread were found. This suggests that flax fabrics may be found additionally if the hardened lumps of fabrics are resolved and analyzed. Other materials discovered include knits, knotted strings, embroideries, threads and floss. Pieces considered knits and knotted strings occupy a large part of fabrics excavated from King Muryeong's Tomb, and in particular knotted strings show various knotting methods. In addition, embroideries such as chain stitch and button hole stitch are clearly observed. What is more, there are silk threads and hemp threads, which are presumed to have been used for dangling ornaments such as Yeongrak(瓔珞) and beads or for sewing. Besides, floss was found between fabrics.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.469-474
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• 2008

The objective of this study is to propose basic design guidelines for more effective air ventilation system in apartments. It is well known that ventilation depends on whether the room doors are open or closed as well as people's living patterns. This study considers 84 ㎡-sized apartment which has extended living room without balcony. Ventilation of bathroom and kitchen is not considered. The height of the building, external air pressure and air infiltration through the windows are also neglected. The regulation on indoor air quality made it mandatory that the air change per hour be more than 0.7. Four models are suggested to study the effect of open and closed doors. Models 1 and 3 are open door types and models 2 and 4 are closed door types. The open types have 50 mm hole near the top of the door to substitute exhaust outlet. The ventilation effectiveness was evaluated by 3-dimensional numerical simulation using finite volume method by a commercial software. This work compares air flow, temperature of air, age of air and the efficiency of ventilation of apartments with wooden doors of bedroom 1 and 2, which are open or closed.

• Journal of Korean Association for Spatial Structures
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• v.7 no.5
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• pp.67-74
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• 2007

The unsymmetrically layered artificial material model is consistently introduced to find the optimum topologies of the plate structures. Reissner-Mindlin (RM) plate theory is adopted to formulate the present 9-node plate element considering the first-order shear deformation of the plates. In the topology optimization process, the strain energy to be minimized is employed as the objective function and the initial volume of structures is adopted as the constraint function. In addition, the resizing algorithm based on the optimality criteria is used to update the hole size introduced in the proposed artificial material model. Several numerical examples are rallied out to investigate the performance of the proposed technique. From numerical results, the proposed topology optimization techniques are found to be very effective to produce the optimum topology of plate structures. In particular, the proposed unsymmetric stiffening layer model make it possible to produce more realistic stiffener design of the plate structures.

• Nuclear Engineering and Technology
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• v.45 no.7
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• pp.941-950
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• 2013

The Korean Nuclear-Hydrogen Technology Development (NHTD) Plan will be performing irradiation testing of coated particle fuel at HANARO to support the development of VHTR in Korea. This testing will be carried out to demonstrate and qualify TRISO-coated particle fuel for use in VHTR. The testing will be irradiated in an inert gas atmosphere without on-line temperature monitoring and control combined with on-line fission product monitoring of the sweep gas. The irradiation device contains two test rods, one has nine fuel compacts and the other five compacts and eight graphite specimens. Each compact contains about 260 TRISO-coated particles. The irradiation device is being loaded and irradiated into the OR5 hole of the in HANARO core from August 2013. The device will be operated for about 150 effective full-power days at a peak temperature of about $1030^{\circ}C$ in BOC (Beginning of Cycle) during irradiation testing. After a peak burn-up of about 4 atomic percentage and a peak fast neutron fluence of about $1.7{\times}10^{21}\;n/cm^2$, PIE (Post-Irradiation Examination) of the irradiated coated particle fuel will be performed at IMEF (Irradiated Material Examination Facility). This paper reviews the design of test rod and irradiation device for coated particle fuel, and discusses the technical results for irradiation testing at HANARO.

• Nuclear Engineering and Technology
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• v.45 no.2
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• pp.257-264
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• 2013

In Canada Deuterium Uranium (CANDU)-type nuclear power plants, the reactor is composed of 380 fuel channels and refueling is performed on one or two channels per day. At the time of refueling, the fluid force of the cooling water inside the channel is exploited. New fuel added upstream of the fuel channel is moved downstream by the fluid force of the cooling water, and the used fuel is pushed out. Through this process, refueling is completed. Among the 380 fuel channels, outer rows 1 and 2 (called the FARE channel) make the process of using only the internal fluid force impossible because of the low flow rate of the channel cooling water. Therefore, a Flow Assist Ram Extension (FARE) tool, a refueling aid, is used to refuel these channels in order to compensate for the insufficient fluid force. The FARE tool causes flow resistance, thus allowing the fuel to be moved down with the flow of cooling water. Although the existing FARE tool can perform refueling in Korean plants, the coolant flow rate is reduced to below 80% of the normal flow for some time during refueling. A Flow rate below 80% of the normal flow cause low flow rate alarm signal in the plant operation. A flow rate below 80% of the normal flow may cause difficulties in the plant operation because of the increase in the coolant temperature of the channel. A new and improved FARE tool is needed to address the limitations of the existing FARE tool. In this study, we identified the cause of the low flow phenomena of the existing FARE tool. A new and improved FARE tool has been designed and manufactured. The improved FARE tool has been tested many times using laboratory test apparatus and was redesigned until satisfactory results were obtained. In order to confirm the performance of the improved FARE tool in a real plant, the final design FARE tool was tested at Wolsong Nuclear Power Plant Unit 2. The test was carried out successfully and the low flow rate alarm signal was eliminated during refueling. Several additional improved FARE tools have been manufactured. These improved FARE tools are currently being used for Korean CANDU plant refueling.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.3
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• pp.315-320
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• 2010

In this paper, an internal TDMB(Terrestrial Digital Multimedia Broadcasting) antenna for mobile phone is proposed. The overall dimension of designed antenna with substrate is 30 mm$\times$5 mm$\times$0.6 mm. The proposed antenna consists of a meander type radiator which is connected front- and back-plane of Kapton substrate by via hole and parasitic element for tuning the resonant frequency. And to compensate the electric length of desired frequency, passive inductor is used for matching element. Measured gain of the implemented antenna -17.6 dBi at 174 MHz, -13.01 dBi at 195 MHz, and -14.9 dBi at 216 MHz.

• Journal of the Korean GEO-environmental Society
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• v.9 no.2
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• pp.61-65
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• 2008

In this study, a newly modified soil nailing technology named as the PGSN (Pressurized Grouting Soil Nailing) system is proposed. Effects of various factors related to the design of the pressurized grouting soil nailing system, such as the length of re-bars and type of reinforcement materials, were examined throughout a series of the displacement-controlled field pull-out tests. 9 displacement-controlled field pull-out tests were performed and the ratio of injected grout volume to grout hole volume were also evaluated based on the measurements. In addition, short-term characteristics of pull-out deformations of the newly proposed PGSN system were analyzed and compared with those of the ordinary soil nailing system by carrying out field pull-out tests. The test results were shown that the displacements of pressurized grouting soil nailing system were decreased 30~36% in comparison with using gravity grouting soil nailing system by the pressurized effect. The displacements of steel tube were diminished 31~32% comparison with using deformed bar by the reinforcement type change from the field pull-out tests.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.5
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• pp.38-50
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• 2010

Expressways are often upgraded by widening the lanes and/or by reshaping the roads to be more linear for faster travel time. However, during the process of improving the route of the expressways, the areas where the old expressways used to be are often unused and abandoned. When these neglected sites are left alone, they often become dump sites causing pollution and impacting the surrounding environment. Therefore, it is important to restore the abandoned expressway sites to its full natural beauty. In this study, the abandoned expressway at the Soksa interchange in Pyungchang county, located in Kangwon province was studied for establishing the model of ecological restoration project. Considering the characteristics of the site, the target flora species was chosen to be Quercus species and the target fauna species as amphibians. After the target species were carefully chosen, each species' habitat requirements were studied in order to figure out the appropriate methods toward habitat restoration specifically for these species. In addition, to determine the most efficient method toward restoration of abandoned expressways, the study utilized the planting hole techniques, the crack techniques, and the colonization techniques. In terms of the spatial organization, public education program is incorporated at the main entrance area and the programs for experimenting, and developing vegetation and habitat restoration techniques are placed in the vicinity. In the master plan-to provide natural ecosystem at the site-ASCON (asphalt concrete) was removed first, then plans for restoration including species' habitat restoration were established. Furthermore, the project included plans for improving water quality polluted through non-point source considering the surrounding nearby road and farm lands. Finally, the study established a planning process that will experimentally apply to the abandoned expressway restoration method. In the future, there will be a continuous monitoring of the methods applied to verify if the restoration methods are effective. Also, new restoration techniques should be available according to a variety of abandoned expressways' characteristics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.5974-5979
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• 2014

Lightweight parts with very uniform precision are manufactured by an indent method and the press technique has been improved. Upon assembly with an indent method, a deformation force due to the compressive force occurs between the pin and hole and the contact surface is affected by damage. Therefore, a 3 dimensional model was made using the CATIA program and the damage on the surface contacted with indent was estimated through the ANSYS program in this study. In the analysis result, the maximum load applied at the PCB plate was 21.3 N when the pin goes through the PCB plate. When PCB plate came out of the pin, the maximum load was 19.24 N. As the structural analysis result, the maximum equivalent stress of Pin 1 was 192.96MPa because the maximum stress occurs at Pin 1 among all parts of this study model. By examining the damage property of the contacted indent and applying this study result to the design of real indentation, the damage can be prevented and the durability can be estimated.