• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.361-370
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• 2020

We developed a heavy-duty work class ROV trencher named URI-T (Underwater robot it's trencher) that can conduct burial and maintenance tasks for underwater cables and small diameter pipelines. It requires various supporting systems, including a dynamic positioning (DP) vessel, launch and recovery system (LARS), A-frame, and winch in order to perform burial tasks because of its dimensions (6.5 m × 5.0 m × 4.5 m, 20 t) and the tough working environment. However, operating a DP vessel has disadvantages as it is expensive to rent and operate and it is difficult to adjust the working schedule for some domestic coast construction cases. In this paper, we propose a method using a barge instead of a DP vessel to avoid the above disadvantages. Although burying the cable and pipeline using a barge has lower working efficiency than a DP vessel, it can save construction expenses and does not require a large crew. The proposed method was applied over two months at the construction of the water supply in Yokji-do, and the results were verified.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.197-203
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• 2015

Nuclear power plant has increased continuously for power production in all over the world and the interest about nuclear accident and the dismantling of aging nuclear power plant has been a growing. The leaked radioactive source that is generated by radiation accidents must detect and remove to minimized the damage as soon as possible. Gamma-ray detection system that have been developed until now cannot provide the precise position of radioactive sources because they detect and imaging the position of radiation sources in just two dimensions. In this paper, stereo gamma ray detection system has developed and the algorithm for calculation of the distance has implemented to be able to measure the distribution of the leakage gamma ray source for the system. Stereo camera calibration for distance detection was conducted with the correction pattern and LED light and we carried out performance test of the system for the LED light source and a gamma ray source. In both experiments the results of the performance test, it was confirmed to have a 5% error. The results of this paper is used as a material for the development of gamma-ray imaging device.

• Review of Culture and Economy
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• v.21 no.3
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• pp.89-124
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• 2018

Although design industry belongs to one of the creative industries and contributes significantly to urban cultural economy based on its cluster formation, researches on design industry are rarely made explicit from the perspective of creative industry cluster. After reviewing the life cycle of design industry clusters in Euljiro and Hongdae Area in Seoul, this study compares these two clusters with respect of diverse dimensions of creative industry cluster such as agglomeration economy, spin-off activities and institutional environments. Research methodology includes the analysis of ?Seoul Business Statistics? and the in-depth interviews with 14 professional designers. The result shows that design industry cluster in Euljiro is close to the traditional industry cluster mainly dependent on printing industry with very limited impact on urban economy, while Hongdae Area develops creative industry cluster by virtue of university spin-offs, art markets, hybrid cultural consumption spaces and the active participation of designers contributing to urban economy in diverse ways. This comparative analysis highlights the importance of various environmental components to encourage creative activities in developing the creative industry cluster.

• Journal of the Korea Convergence Society
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• v.10 no.11
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• pp.173-179
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• 2019

DICOM(Digital Imaging and Communications in Medicine) imaging plays a significant role in the diagnosis and treatment of the human body, and design modeling is a technology of planning shapes in three dimensions according to the purpose. In this study, we converge these two technologies to observe the relationships of the cross-section, volume, and surface area to the morphological changes of the external ear canal. The experiment applied medical imaging technologies to acquire sections of the human body to create and divide centerlines using 3D shapes extracted from 19 external ear canals by applying stereolithography and 3-matic program. The results showed that the cross-sectional structure of the external ear canal had various shapes, such as oval (38.5%), semicircular (28.2%), mixed (17.9%), square (10.2%), and wrinkled (5.1%). In addition, the cross-sectional area of each phase increased as the length of the external ear canal increased, and the volume and surface area decreased towards the direction of the eardrum. However, the surface area reduction rate was relatively low. This indicates that the structure becomes irregular towards the direction of the eardrum.

• Journal of Digital Convergence
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• v.17 no.10
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• pp.199-207
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• 2019

This study utilized one of Hofstede's cultural dimension, collective dimension and validated its influence on individual's change oriented organizational citizenship behavior(COCB hereafter) with mediation of emotional regulation. Previous research on Hofstede's cultural dimensions were mostly conducted at national levels. However, in this study, Yoo's CVSCALE was used to analyze collectivistic tendencies at individual levels and its influence on emotional regulation and COCB were measured. The study distributed 200 paper based self administered surveys to employees of Fortune 500 electronic company in Korea for two weeks period. Findings indicated individual's collectivistic dimension positively influenced COCB and emotional regulation mediated between collectivism and COCB. In conclusion and application, the significance of this research lies in indicating collectivistic culture's positive influence on COCB and emotional regulation as possible antecedents of Change oriented Organizational Citizenship Behavior.

• Earthquakes and Structures
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• v.8 no.1
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• pp.275-304
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• 2015

The objective of this paper is to investigate the validity of transmitting boundaries in dynamic analysis of soil-structure interaction problems. As a case study, the proposed Baghdad metro line is considered. The information about the dimensions and the material properties of the concrete tunnel and surrounding soil were obtained from a previous study. A parametric study is carried out to investigate the effect of several parameters including the peak value of the horizontal component of earthquake displacement records and the frequency of the dynamic load. The computer program (Mod-MIXDYN) is used for the analysis. The numerical results are analyzed for three conditions; finite boundaries (traditional boundaries), infinite boundaries modelled by infinite elements (5-node mapped infinite element) presented by Selvadurai and Karpurapu, 1988), and infinite boundaries modelled by dashpot elements (viscous boundaries). It was found that the transmitting boundary absorbs most of the incident energy. The distinct reflections observed for the "fixed boundaries" disappear by using "transmitted boundaries". This is true for both cases of using viscous boundaries or mapped infinite elements. The type and location of the dynamic load represent two controlling factors in deciding the importance of using infinite boundaries. It was found that the results present significant differences when earthquake is applied as a base motion or a pressure load is applied at the surface ground. The peak value of the vertical displacement at nodes A, B, E and F (located at the tunnel's crown and side walls, and at the surface above the tunnel and at the surface 6.5 m away from tunnel's centre respectively) increases with the frequency of the surface pressure load for both cases 1 and 2 (traditional boundaries and mapped infinite elements respectively) while it decreases for case 3 (viscous boundaries). The modular ratio Ec/Es (modulus of elasticity of the concrete lining to that of the surrounding soil) has a considerable effect on the peak value of the horizontal displacement at node B (on the side wall of the tunnel lining) increase about (17.5) times, for the three cases (1, 2, and 3).

• Steel and Composite Structures
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• v.9 no.4
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• pp.349-366
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• 2009

The composite slim beam has become popular throughout Europe in recent years and has also been used on some projects in China. With its steel section encased in a concrete slab, the steel-concrete composite slim beam can provide the floor construction with minimum depth and high fire resistance. However, the design method of the T-shape steel-concrete composite beam is no longer applicable to the composite slim beam with deep deck for its special construction, of which the present design models are not available but mainly depend on experiences. The elevation of the flexural stiffness and bending capacity of composite slim beams with deep deck is rather complicated, because the influences of many factors should be taken into account, such as the variable section dimensions, development of cracks and non-linear characteristics of concrete, etc. In this paper, experimental investigations have been conducted into the flexural behavior of two specimens of simply supported composite slim beam with deep deck. The emphases were laid on the bonding force on the interface between steel beam and concrete, the stress distribution of beam section, the flexural stiffness and bending capacity of the composite beams. Based on the experimental results, the reduction factor of equivalent stress distribution in concrete flange is suggested, and the calculation method of flexural stiffness and bending capacity of simply supported slim beams are proposed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.3
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• pp.208-215
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• 2011

A full-scale field trial in ice-covered sea is one of the most important tasks in the design of icebreaking ships. The first Korean icebreaking research vessel 'ARAON', after her delivery in late 2009, had a sea ice field trial in the Arctic Sea during July-August, 2010. This paper describes the test procedures and data analysis on the icebreaking performance of the IBRV ARAON. The data gathered from the icebreaking performance test in the Chukchi Sea and the Beaufort Sea during the Arctic voyage of ARAON includes the speed and engine power of the ship as well as sea ice thickness and strength data. The air temperature, wind speed and heading of the ship were also measured during each sea ice trial. The ARAON was designed to break 1 m thick level ice with a flexural strength of 630kPa at a continuous speed of 3knots. She is registered as a KR POLAR 10 class ship. The principal dimensions of ARAON are 110 m, 19 m and 6.8 m in length, breadth and draft respectively. She is equipped with four 3,500kW diesel-electric main engines and two Azipod type propulsion motors. Four sea ice trials were carried out to understand the relationship between the engine power and the ship speed, given the Arctic ice condition. The analysis shows that the ARAON was able to operate at 1.5knots in a 2.5m thick medium ice floe condition with the engine power of 5MW, and the speed reached 3.1 knots at the same ice floe condition when the power increased to 6.6MW. She showed a good performance of speed in medium ice floe compared to the speed performance in level ice. More detailed analysis is summarized in this paper.

• Journal of the Korea Society of Computer and Information
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• v.11 no.4 s.42
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• pp.243-250
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• 2006

A recursive relationship is a relationship among entities of the same class. N : M recursive relationships can be used to represent bills of materials. A bill of materials is a special data structure that occurs frequently in manufacturing applications. This data structure is a hierarchy. Most business dimensions have a hierarchical structure. In this study, a design of a hierarchical dimension of the bill of materials type is carried out. As with other N : M relationships, an intersection table that shows pairs of related rows is created, and this table is transformed into a dimension in the OLAP(OnLine Analytical Processing) model. This transformation consists of two tasks: (1)replacing the first column of the intersection table with the lowest level of the dimension: and (2)replacing the second column of the table with the only upper level of the dimension. A case multidimensional information system using the hierarchical dimension is also developed.

• The Journal of Advanced Prosthodontics
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• v.13 no.5
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• pp.304-315
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• 2021

PURPOSE. Esthetic expectations have increased the use of polyetheretherketone (PEEK) clasps as alternatives to Cr-Co in removable partial dentures (RPDs). The objective of this study was to evaluate the retentive force and dimensional change of clasps with different thickness and undercut made from PEEK by the thermo-mechanical fatigue. MATERIALS AND METHODS. PEEK clasps (N = 48) with thicknesses of 1 or 1.50 mm and 48 premolar monolithic zirconia crowns with undercuts of 0.25 mm or 0.50 mm were fabricated. Samples are divided into four groups (C1-C4) and were subjected to 7200 thermal aging cycles (at 5 - 55℃). The changes in the retentive force and dimensions of the clasps were measured by micro-stress testing and micro-CT devices from five measurement points (M1 - M5). One-way ANOVA, paired t-test, two-way repeated ANOVA, and post-hoc tests were used to analyze the data (P < .05). RESULTS. The retentive forces of C1, C2, C3, and C4 groups in initial and final test were found to be 4.389-3.388 N, 4.67 - 3.396 N, 5.161 - 4.096 N, 5.459 - 4.141 N, respectively. The effects of retentive force of all PEEK clasps groups were significant decreased. Thermo-mechanical cycles caused significant dimensional changes at points with M2, M4, and M5, and abraded the clasp corners and increased the distance between the ends of the clasp, resulting in reduced retentive forces (P^* = .016, P^* = .042, P < .001, respectively). CONCLUSION. Thermo-mechanical aging decreases the retentive forces in PEEK clasps. Increasing the thickness and undercut amount of clasps decreases the amount of dimensional change. The values measured after aging are within the clinically acceptable limits.