• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.408-413
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• 2004

High speed planning boats also have been required more and more the rational strength analysis and evaluation for the optimal structural design in respect of the structural lightness according to the high speed trend. Even though the suggestion of the simple type equation for the equivalent dynamic pressure is reasonable to design the scantling of ship structure conveniently, many research activities for more reasonable improvement of the simple design pressure, have been continued to suggest the more accurate equivalent static description of tire structural response such as the deflection and stress of hull structure. In this research, we focus on the aluminum bottom stiffened plate structure in which structural scantling is mainly depend on the local loads such as dynamic or impact pressure without other load effects and structural response for the simple dynamic equivalent pressure was investigated through the structural analysis. In order to investigate the structural response of the bottom stiffened plate structure subjected to the dynamic equivalent design pressure, linear and nonlinear structural analysis of the bottom stiffened plate structure of 4.3 ton aluminum planning boat was performed based on the equivalent static applied loads which were derived from the KR regulation and representative one among various dynamic equivalent pressure equations. From above analysis results, we found that the response such as deflection and stress of plate member was similar with the response results of one plate member model with fixed boundary, which was published previous paper and in case of KR design loading, all response of stiffened plate structure were within elastic limit. Through the nonlinear analysis, nearly elastic behavior including the slight geometrical nonlinear response was dominant but plastic local zone was appeared at $85\%$ limit load. Therefore, we can say that through tire linear and nonlinear analysis, this stiffened plate member has no structural strength problem based on the yield criteria in case within $60\%$ limit load except the other strength point of view such as the fatigue and buckling problem.

• Journal of Korea Port Economic Association
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• v.27 no.1
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• pp.281-304
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• 2011

In the energy-climate era, pollution emissions from port activities have a significant issue in international shipping and port community. Thus international organization such as IMO and developed countries are seeking to develop various reduction strategies against air pollution. However Korea has recently conducted several studies concerning air pollution in port industry. The main purpose of the paper is to suggest emission reduction strategies for bulk terminal in Port of Incheon, which handles large amount bulk cargoes as a gateway for the metropolitan area. For this aim, the clean air strategies of the world major ports were considered and air pollution reduction strategies were suggested. The main findings of this paper are as follows. First, the emission reduction strategies for container terminal are should be integrated based on technologies changes, operational changes and market-based measures. Second, the emission reduction strategies for bulk terminal can be effective when use innovative measures during loading, unloading and storage process such as telescopic cascade trimming chute, snake sandwich equipment, dry fog system and dome structure. Finally, investigation on actual conditions of air pollution in Korean ports and development of environmental evaluation scheme for persisting monitoring should be conducted.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.477-485
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• 2010

Various monitoring sensors are used to predict and detect structural damage. Smart sensors, such as glass-fiber sensors, PZT, and MEMS, among others, have replaced traditional sensors. They are now being used in many areas. This study aims to predict the damage by measuring the PZT voltage attached on the specimen by the applied impact load. In the experiment to detect damages in beam connection, simple $H-400{\times}200{\times}8{\times}13$ beams were spliced with bolts. The results of FFT between PZT sensor and accelrometer were compared to measure the sensitivity of the PZT sensor. The damage to the beam was presumed by loosening the bolt, and then the damage measurement was accompanied. Secondly, a steel $PL600{\times}65{\times}5.8$ plate beam was fabricated for the purpose of experimenting on damage measurement. Impact loading test on three different locations was carried out. Damage width varied between 6~42mm on both sides by cutting, using a steel saw. The ratio of frequencies before and after the damage was computed to quantify the damage level by using FFT, and the change in mode pattern with the increased damage was investigated to measure the damage.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.667-675
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• 2012

Flat plate are being used more in buildings requiring a high level of technical installations or in buildings needing changeable room arrangements during their life time such as office buildings. The main problem in flat plate is its weak resistance against a punching failure at its slab-column connections. Therefore, in this research, an experimental study on full-scale interior slab-column connection was performed. Three types of shear reinforcements were tested to prevent brittle punching shear failure that could lead to collapse of the structure. A series of four flat plate specimens including a specimen without shear reinforcement and three specimens with shear reinforcements were tested. The slabs were tested up to failure using monotonic vertical shear loading. The presences of the shear reinforcements substantially increased punching shear capacity and ductility of the interior slabcolumn connections. The test results showed that a slab that did not have enough bond length failed before shear reinforcement yielded due to anchorage slip. Also, FEM analyses were performed to study an effect of slab thickness and concrete compressive strength on the flat plate slab. The analytical study results were used to propose a method to calculate performance capacity of shear reinforcement in slab-column connection.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.4
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• pp.345-356
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• 2011

Based on the consideration of land based pollutant discharges from the basin and seawater quality related carrying capacity and the seawater quality improvement in receiving water bodies of Yeoja Bay where eutrophication and organic pollution are in progress, were evaluated. The permissible inflow loads of BOD, TN and TP by using the geographical features and box modelling method were estimated. As results, it is shown that the reduction rate of discharged BOD and TP loads were 39.3% and 30.8 %, respectively, however, 6.9% was estimated for TN. According to the pollutant loading in each tributary and generated load of the basin, it is given much weight on the land use group, and also was shown in discharged load estimation. This suggests that it is important to control nonpoint source pollutant such as livestock and land use groups as well as point source to contribute the proposition of the water quality improvement plan according to the characteristics of the bay.

• Journal of Korean Academy of Nursing
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• v.29 no.2
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• pp.215-224
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• 1999

The study was conducted to centum the construct of individual perception and preference for work characteristics as personal factors influencing Korean nurses' job satisfaction. The subjects of the study were 231 nurses who are currently working in intensive care units and have been for a minimum of 6 months. The study used the Staff Perception and Preference Scale(Song et al., 1997) to measure the individual's perception and preference on the technical. practice. and management components of the ideal work environment. The Korean version of the Staff Perception and Preference Scale consists of 16 items on perception and 13 on preference with each item related on a scale from 1(not at all) to 4(a great deal). Psychometric testing revealed that the preference and perception scale is internally consistent with Chronbach's alphas of .83 for perception scale arid .80 for preference scale. The subscales of the perception and preference scale also showed acceptable reliability for the early stage of the development of the instruments with Chronbach alphas of .62-.76 and .69-.83 respectively. Criterion-related validity of the scale was tested by examining correlations with individual growth need that is conceptually close to individual preference. but not to individual perception. Individual growth need was significantly related to individual preference(r＝.63, p<.05), but the correlation with the perception scale was not significant. A separate factor analysis for the each of perception and preference scales was performed with a three-factor loading solution based on a previous study. The results on the staff perception scale confirmed with varimax rotation that the items were cleanly and strongly loaded on technique. practice and management components, which together explained 50.7% of the variance. The factor analysis on the staff preference scale also yielded a three factor solution that explained 56.7% of the variance. but items on technique and management components were loaded together. This phenomena may due to the current nursing delivery system in Korea where nurses never experience either shared governance nor case management, and as a results they may not be able to consider management roles as their potential extended roles. Therefore, more efforts should be given to enhance nurses' autonomy and decision making in the technique, practice and management components of their work environment. Meanwhile, there is a need for continuously confirming and developing tools for individual perception and preferences to effectively enhance job satisfaction among Korean nurses through innovative work environments.

• Journal of Digital Convergence
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• v.13 no.8
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• pp.281-288
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• 2015

The container terminals use convergence technology that exchange information for cargo work, using wireless communication between the TOS(Terminal Operations System) and the handling equipments(CC, TC, YT). But if the container cargoes pile up high in the container yard, delayed cargo work and cargo working list information error happen because of communication dead spots(the worker can not receive the information) which wireless communication is disconnected. At this time the driver of the yard tractor(YT) must be able to recognize the communication state. If then, delayed cargo work and cargo working list information errors that occur in the shaded communication area can be avoided, and can process the delayed work due to wireless communication break. In this project, we have built wireless communication environment to increase the efficiency of the loading and unloading operations which the operator can respond actively, when the work is delayed and work orders result in errors. That is, the flow of the wireless communication module has been changed.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.5
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• pp.38-43
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• 2015

In this paper, we present novel dual-band microstrip antennas using inverted-L-shaped parasitic elements vertically at radiation apertures for GPS L1(1.575 GHz) and L2(1.227 GHz) bands. For making dual band which has large interval, the inverted-L-shaped parasitic element was loaded at the radiation aperture of a half-wavelength patch antenna(GPS L1) in opposite direction of the feeding point for receiving the low frequency(GPS L2). The low frequency occurs by perturbation and coupling between the patch and parasitic. Next, due to use circular polarizations at the GPS applications, two inverted-L-shaped parasitic elements were loaded at radiation apertures of each polarizations and the feeding point was moved at diagonal part of the patch. The dimensions of the designed circularly polarized antenna were $88.5{\times}79{\times}10.4mm^3$ ($0.36{\lambda}L{\times}0.32{\lambda}L{\times}0.04{\lambda}L$, ${\lambda}L$ is the free-space wavelength at 1.227 GHz). Measured -10 dB bandwidths were 116.3 MHz(7.4%) and 64.3 MHz(5.2%) at GPS L1 and L2 bands, respectively. All of these cover the respective required system bandwidths. The measured 3 dB axial ratio bandwidths were 11.7 MHz(0.74%) and 14 MHz(1.14%), respectively. Within each of the designed bands, broadside radiation patterns were observed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.10-19
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• 2016

The objective of this study is to investigate the self-healing properties of ternary blended cement(TBC) paste made with OPC, GGBFS and FA. The influence of OPC-GGBFS-FA on the self-healing ability of ternary blended cement paste was researched by ultrasonic pulse velocity(UPV) measurement. The TBC paste with GGBFS-FA replacement ratios of 20%, 40% and 60% were prepared having a constant water-cementitious materials ratios os 0.5. The research focuses on behavior after 28days(after loading). Four-point bending tests are used to pre-cracked the prismatic specimens at 28days. For specimens (uncracked and cracked) submerged in tap-water and sea-water until 60days. According to the experimental results, the TBC paste system has self-healing ability increased when the fraction of GGBFS increased. Because GGBFS and FA continues to hydrate after 28days, it is likely that hydrated products from GGBFS and FA may modify microstructures, seal these cracks. From these results, it is clear that the crack in all samples experience self-healing and that this occurs mostly in the first 30days of submerging. Futhermore, most of the healing for both specimens of submerged in sea-water and tap-water occurred during the first 30days. Sea-water submerged specimens healed cracks as fast as those in tap-water. Differences in healing effects of submerged in sea-water and tap-water may be attributed to the presence of specific sea-water ions. Therefore, self-healing effects considered age-effects was more strong effect occurred mostly in the first 30days, and then gradually weaken.

• Journal of the Korean Geosynthetics Society
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• v.15 no.3
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• pp.67-76
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• 2016

The railway bridge abutment subjected to the lateral earth pressure is a sensitive structure that is affected by backfill materials, installation methods, compaction, and drainage system and so on. The several design loads for the bridge abutment design consist of traffic loading on bridges and vertical & lateral force due to surcharge load at backfill. Especially, the lateral earth pressure of design load components is important and considered in the design of geotechnical engineering structure such as bridge abutment wall. The determination of cross section for abutment is finally determined with calculating external stability and member force of abutment wall structures. In this study, the abutment wall height is 12m and the optimal cross section of abutment wall has been determined that satisfies an external stability for abutment structure through friction angles of 35, 40, and 45 degrees of backfill materials. The external stability and member force of abutment wall with friction angle of backfill materials and were calculated and construction cost of each abutment wall structures was compared. It found that the construction cost was reduced from 2.2 to 8.4% with friction angle of backfill materials.