• Journal of the Korean Geotechnical Society
• /
• v.17 no.6
• /
• pp.163-171
• /
• 2001

It is important to pay careful attention to the backfill construction for the structural integrity of concrete box culvert. To increase the structural integrity of culvert good compaction by the dynamic compaction roller with big capacity is as effective as good backfill materials. However structural distress of the culvert could be occurred due to the excessive earth pressure by great dynamic compaction load. In this study, two box culverts were constructed with change compaction materials and construction methods. Two type of on-site soils such as subbase and subgrade materials were used as backfill materials. In most case, dynamic compaction rollers with 11 to 12 ton weights were used and vibration frequency were applied from 2000 to 2500 rpm for the great compaction energy. Backfill compactions with good quality soils were carried out to examine the effect of cushions on dynamic lateral soil pressure. Expanded polystyrene (EPS) and rubber of tire were adapted as cushion materials and they are set on the culverts before backfill construction. This paper presents the main results on the characteristics of dynamic earth pressures. Test result indicates that the amounts of increased dynamic pressures are affected with backfill materials, depth of pressure cell, and compaction condition. The earth pressure during compaction can give harmful effect to box culvert because the value of dynamic earth pressure coefficient $(\DeltaK_{dyn}=\DeltaK\sigma_h\DeltaK\sigma_v)$ during compaction is greater than that of static condition. It was observed that cushion panels of EPS(t=10cm) and rubber(t=5cm) are effective to mitigate dynamic lateral pressure on the culverts.

• Archives of design research
• /
• no.18
• /
• pp.165-174
• /
• 1996

In the I950s the German firm Braun began to pursue a policy of uncompromising modem design for products aimed at the upper reaches of the market. Dr. Fritz Eichler as a head of design with Hans Gugelot and Otl Aicher in the Graduate School VIm developed the guide line of Braun Design strategy as the foundation of the corporate identity programme. In 1955 Dieter Rams joined the staff, and was largely responsible for establishing the formal characteristics of Braun Design and its further development. In the mid-1950s complete product programme of the firm Braun began to be re-designed, and these undoubtedly hit the market. New design line of the firm Braun, was an exclusive avantgarde movement at that time, which became to be the epitome of the idea of an objectifiable "Good Form". By the result in the 60s and 70s, when Braun product program was completely re-designed to the new line, Braun Design had a decisive influence on the design scene of the world. Braun Design is essentially functional and concrete, which depends on perfect fulfillment of purpose, precision, safety, durability, the quality of the product and, more recently, environmental compatibility is similarly balanced and unified approach, eliminating every unnecessary detail and concentrating on ordering essential elements. elements.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.5 no.3
• /
• pp.275-281
• /
• 2017

This study is to investigate experimentally the effect of refining of fly ash (FA) on the engineering properties of the cement mortar. Five different FAs are used including raw fly ash, refined fly ash, reject ash and their two different combinations. The cement mortars are fabricated with 1:1(binder to fine aggregate), 1 : 3 and 1 : 5 respectively, which are replaced 30% of FA by cement. Test results, indicated that, the flow of Ra showed lower flowability than Rf at all mixing ratios. Also in the case of Rj, it was expected to show low fluidity, but it showed flowability equal to or higher than Rf. Air contents are all formulations except Rf and Rj did not satisfy the target range. Using Ra, the refining process shows an air amount about 41% lower than Rf, in the case of Rj, it showed about 19% higher air content than Rf due to porous foreign matters inside the mortar. Compressive strength was in the early days 3 and 7, the strength was lower than that of Plain's OPC, after 28 days Rf exerts higher strength than other FAs, it was confirmed that higher strength than OPC can be secured at a mixing ratio of 1: 1 and 1: 3. For frost resistance, the use of unrefined FA resulted in decrease of frost resistance sharply due to loss of air content by the use of unrefined FA. Therefore, it is considered that the use of high quality FA through refining process will contribute positively to the economical formulation of concrete and the stability of the structure.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.7
• /
• pp.474-480
• /
• 2018

FRP is a new material that is lightweight, has high strength and high durability, and is emerging as a third construction material in many countries. The composite material panel targeted in this study was a curved member and is the most frequently used arch-shaped member of a structures, such as tunnels. Composite curved panels can be produced in high quality and large quantities through automation operations. On the other hand, the frequency of application is low, and the design criteria and experimental data are lacking. Therefore, this study examined the mechanical performance of the member unit first to verify its performance as structural members of the FRP curved panel. For this purpose, tensile, compression, and connection performance tests were carried out. The tensile tests showed greater tensile strength of specimens with larger curvature, and the compression tests showed that the composite section of a composite material has greater compressive strength than the concrete section. Finally, the test of the performance of the connection showed that the attachment performance of the connection was more than equal to that of the FRP composite material panel.

• The Journal of the Korea Contents Association
• /
• v.18 no.10
• /
• pp.631-643
• /
• 2018

This study is the first ever attempted series paper of one particular TV drama writer, Su-Hyeon Kim, with diversified and systematic scale. Along with the just before study, proving Su-Hyeon Kim's line's conceptual properties as the Bahktin's dialogism, its core of polyphony, this study is to analyze the concrete method of creation through Bahktin's Canivalistic creation component of 'Grotesque Realism' and 'Unofficial Square Language'. With her work of (SBS, 1992), this study verifies its characteristic creation of lines to be the 'Grotesque Realism' components of overturn, destruction, and creation along with 'Unofficial Square Language' components of the masses, material, physical language, and discourse of self-liberation. In this way, this study is on one hand, to overcome the application problem of Bahktin's theory as a separated one, but also to enhance the quality of the study of the writer and the lines. As a result, she has acquired her own distinction of ambivalence by the way of demotion, overturn with masses' material, physical, unofficial square language along with a stronger execution of acquiring self denial, positivity. liberation, and life. Therefore the writer is highly rated for her fierce cognition of language and her artistic spirit. Also, this paper proposes the following study to appraise the impact of the writer's differentiation and artistic spirit on the creation of Korean TV drama, contents industry, and mass media.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.5
• /
• pp.738-744
• /
• 2017

Recently, the installation of energy storage systems (ESSs) has increased in parallel with the extension of renewable energy resources. However, there has been no concrete analysis ofthe performance verification and economic evaluation of ESSs,which makes it difficult to perform aneffective installation and operation of an ESS. In particular, there are no international technical standards and guidelines on electric ESS for frequency regulation applications. Therefore, acomprehensive study on the power quality, impact on grid, extent of contribution, and cost benefit study of ESS are strongly being required. Under these backgrounds, this paper proposes a performance verification algorithm on ESS for frequency regulation application based on ananalysis of the AGC(Automatic Generation Control) performance verification method of PJM in USA. In addition,this paper proposes an economic evaluation algorithm on a 500 MW installation of ESS for frequency regulation applications using the account settlement of an expensive gas-fired generation plant and coal-fired power generation plant. From the simulation with real ESS operation data and 500 MW installation case, it wasconfirmed that the ESS showssuperior performance toany other conventional generators and provides anannual benefit of 500 MW ESS are between 345~429 billon won.

• Journal of Korean Society of Steel Construction
• /
• v.24 no.3
• /
• pp.267-278
• /
• 2012

In general, the H-shaped steel ribs or triangular lattice girders have been mostly used in constructing tunnels through the NATM construction method. The H-shaped steel rib has higher flexural and axial strength than the triangular lattice girder, but many unexpected gaps can occur in the concrete lining system after shotcreting if the H-shaped steel rib is used as the support system. To achieve better shotcreting quality, the triangular lattice girder was developed. However, in general, the triangle lattice girder has low flexural and axial strength. Likewise, the triangular lattice girder, which has circular sectional members, has so many fractures from welded points at the joints between the members. Finally, the new type of tetragonal lattice girder was developed to overcome those problems. In this study, the structural performance of the tetragonal lattice girders was evaluated through analytical and experimental studies. In the analytical studies, the four-point bending analysis, the traditional evaluation method to determine the flexural strength of the lattice girder, was performed. Moreover, the linear-elastic analysis and stability analysis of the arch structure made by the lattice girders were performed to measure structural performance. Experiments were likewise performed to compare the structural performances of the tetragonal girder with traditional triangular lattice girders.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.2
• /
• pp.33-40
• /
• 2018

Characteristics of interface friction between cohesionless soils and geotechnical structure surfaces play an important role in the analysis of earth load and resistance on the structure. In general, geotechnical structures are mainly composed of either steel or concrete, and their surface roughnesses with respect to soil particle sizes influence the interface characteristics between soils and the structures. Accurate assessment of the interface friction characteristics between soils and structures is important to ensure the safety of geotechnical structures, such as mechanically stabilized earth walls reinforced with inextensible reinforcements, piles embedded into soils, retaining wall backfilled with soils. In this study, based on the database of high quality interface friction tests between frictional soils and solid surfaces from literature, equation representing peak interface friction angle is proposed. The influential factors of the peak interface friction angle are relative roughness between soil and solid surface, relative density of frictional soil, and residual (constant volume) interface friction angle. Futhermore, for the developed equation of the interface friction angle, its uncertainty was assessed statistically based on Goodness-of-fit test results.

• Journal of Technologic Dentistry
• /
• v.30 no.1
• /
• pp.83-96
• /
• 2008

This study aims to analyze the major factors in their working conditions affecting the enlargement of leisure activities of dental technicians. We also present a need for dental technicians to assign more time many different kinds of leisure activities for their quality life. To this end, we examined the status and the characteristics of dental technicians' leisure activities among the randomly selected subjects who are working in the area of Seoul, Gyonggido, and Gangwon-do through the analysis of the 311 sheets of self-administered questionnaires. The conclusions from this analysis are as follows; 1. On weekdays, non participants in leisure activities were found to be 64.0%, and in the case of weekends, the participants were reached to 70.7%. Those who enjoy any leisure activities in either of weekdays and weekends were 34.1%, 27.3% of the dental technicians did not have any leisure activities. Therefore, statistical significance was shown in the participations of leisure activities between weekdays and weekends. 2. Of the types of leisure activities in both weekdays and weekends, sports activities were ranked at the top 33.4%, 29.6% respectively, which is followed by going to the cinema/theatre/exhibitions, etc 21.9%, 26.0%, games/entertainment 14.5%, 14.8%, hobbies/cultural activities 14.1%, 12.5%, sightseeing/picnic 6.4%, 7.4%. 3. Of the differences in the characteristics of leisure activities, the types of leisure activities between weekdays and weekends showed difference in gender, company and information regarding leisure activities in age, company and the place of leisure activities, and leisure information in the marital status, career and monthly income in company, company and leisure information in the job position, which is statistically significant (p<.001). However, no statistical significance was found among the other general items of the characteristics of leisure activities. Considering only works on weekdays policy is currently permeating into almost every business sector, dental business owners or managers are advised to consider more effective time management or human resources management, such as keeping reasonable manufacturing time through cooperations with the dentists, regularity of working hours, incentive system, introduction of credible over time payment. Which will provide their staff with more times and opportunities to enjoy their leisure activities. Additionally, the concrete and feasible ways of motivating and activating the leisure activities of dental technicians are in need of further researches and studies.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.3B
• /
• pp.235-246
• /
• 2009

The number of industry wireless networks based on IEEE 802.11 WLAN technology deployed in large outdoor work sites, such as freight container terminal, is increasing these days. Wider service coverage, frequent movements of stations and high requirement on service reliability are main characteristics of these networks compared to the conventional IEEE 802.11 networks used in home, office and school. While the importance of these networks Bets higher, we can hardly find previous studies including concrete analysis on these networks based on actual experiments. We carried out several field experiments at a freight container terminal to analyze its IEEE 802.11 network and found out some problematic situations, such as over 50% retransmission rates and frequent disruption of communication link while a station is moving. We explain why these problematic situations happen and suggest some solutions, such as application of mesh technology, smart handoff based on location and movement pattern and adjustment of signal strength and channel allocation. Methods and tools used in the experiments are also detailed in the paper which may be helpful for similar future studies.