• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.379-385
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• 2017

In general, distribution board, panel board and motor control center can be installed over a wide area such as residence of group, building, schools, factories, ports, airports, water service and sewerage, substation and heavy industries that are used to supply converts the voltages extra high voltage into optimal voltage. There are electrical accidents due to rise of contact temperature, loose contact between busbar, deterioration of the contact resistance, over temperature of the busbars. In this paper, we designed and implemented the busbar joint and temperature measurement system, which can measure the joint resistance of busbar and loose connection between busbar using potentiometer and non-contact infrared sensor. The experimental results show that tightening the bolt and nut is fully engaged, resistance was decreased and maximum error range was 0.1mm. Also, the experimental result showed that the temperature at the contact area is increased from $27.3^{\circ}C$ to $69.3^{\circ}C$by the contact resistance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.279-285
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• 2019

Transverse vibrations of a ship's aft end and deckhouse are mainly induced by transverse exciting forces from the main engine. Resonance should be avoided in the initial design stages when there is a prediction of resonance between the main engine and transverse modes of the deckhouse. Estimates of frequencies for resonance avoidance are possible from the specifications of the main engine and propeller, but the inherent vibration frequency of the structure around the engine room is not easy to estimate due to the variation in the shape. Experience-oriented vibration design is also carried out, which results in many problems, such as process delay, over-injection of on-site personnel, and iterative performance of the design. For the flexible design of 8,600 TEU container vessels, this study addressed the resonance problem caused by the transverse vibration of the main engine when only the main engine was changed from 12 cylinders to 10 cylinders without modification of the hull structure layout. Efficient structural reinforcement design guidelines are presented for avoiding resonances with the main engine lateral vibration and the structure around the engine room. The guidelines are expected to be used as practical design guidelines at design sites.

• Journal of Practical Engineering Education
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• v.10 no.1
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• pp.73-79
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• 2018

The purpose of this study is to explore the supporting scenario to promote vocational training in North Korea in terms of cooperation level. To this end, we have embarked on a regional and industry based vocational training program by predicting the political and social situation of North Korea and staging three scenarios systematically. These scenarios were designed originally based on the Futures Group methodology. The first scenario is to establish a technical training center in one area, focusing on the electrical, electronics, and clothing sectors. The second scenario is to set up a pilot campus of vocational training college in one region by selecting the electric, electronic, and automobile industries as its main industries. The third scenario is to establish five vocational training college campuses in North Korea, focusing on electricity and electronics, IT manufacturing, telecommunications, heavy industry, and women-specialized industries. We suggested the followings: First, establishing goals and strategies for North Korean vocational training and establishing road maps. Second, the North Korean vocational training governance system needs to be established. Third, R & D infrastructure for vocational training needs to be established. Fourth, HRD and HRM system in North Korea vocational training field needs to be established. In addition, the role of public and private employment services centers to provide them should be strengthening.

• The Journal of the Acoustical Society of Korea
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• v.27 no.3
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• pp.140-148
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• 2008

In this study, a numerical method for a time-domain acoustic wave backscattering analysis is established based on a physical optics and a Fourier transform. The frequency responses of underwater targets are calculated based on physical optics derived from the Kirchhoff-Helmholtz integral equation by applying Kirchhoff approximation and the time-domain signals are simulated taking inverse fast Fourier transform to the obtained frequency responses. Particularly, the adaptive triangular beam method is introduced to calculate the areas impinged directly by acoustic incident wave and the virtual surface concept is adopted to consider the multiple reflection effect. The numerical analysis result for an acoustic plane wave field incident normally upon a square flat plate is coincident with the result by the analytic time-domain physical optics derived theoretically from a conventional physical optics. The numerical simulation result for a hemi-spherical end-capped cylinder model is compared with the measurement result, so that it is recognized that the presented method is valid when the specular reflection effect is predominant, but, for small targets, gives errors due to higher order scattering components. The numerical analysis of an idealized submarine shows that the established method is effectively applicable to large and complex-shaped underwater targets.

• Journal of dental hygiene science
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• v.9 no.1
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• pp.17-23
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• 2009

A survey using a questionnaire was conducted among industrial employees in Ulsan Total surveyed persons was 244. The purpose of this study was to analysis the relation and behavior of oral health promotion. Also, This study was to provide educational data of oral health. The obtained were analysed by SPSS program 12.0. The findings were as below: 1. Dental visit for prevention Y/N(%) was higher 50 years than 20 years(p < .001). Oral hygiene devices Y/N(%) for oral hygiene showed University graduates higher than Middle school graduates respectively(p < .05). 2. The knowledge of oral health was higher High school graduates than Middle school graduates respectively(p < .05). The rate of brushing teeth 3~5 times per day was higher females than males(p < .01) and better College graduates than Middle school graduates respectively(p < .001). 3. Oral health conditions of respondents were better 20years and 30years than 50years respectively(p < .001). Self-evaluation of Oral health sensitive was better College graduates than Middle school graduates respectively(p < .05). 4. Correlation between of Tooth brushing Frequency per Day by Oral health knowledge, dental clinic Visit, Extraction number had an effect on the significant dental clinic visit for prevention and the knowledge of Oral health had even a positive effect relationship(r = .233, p = .001). The knowledge of Oral health and the frequency of tooth brushing had even a positive effect relationship(r = .161, p = .05). The frequency of tooth brushing and the number of extraction of teeth had a negative effect relationship(r = -.145, p = .05).

• Archives of design research
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• v.17 no.1
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• pp.383-392
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• 2004

The power tools is the product using working power generated by electric motor. Many companies are manufacturing numerous devices. Main features of tools are included various assembled products, small, light and solid and durable enough to match several standards. Fundamental requirements for the product is excellent performance and convenience for use. The quality of them depends on the equipped motor'(s) capability, accuracy of gear and endurance against worn-out. By adapting the state-of-the-art parts, they could be used in the place from home to heavy industry broadly. They can be classified electronic drills, grinders, saws and sanders families for the household appliances. For industrial tools, bore drill, grinder, polisher, and driver drill are classified as special and high priced group. This study presents the strategy of power tool development of BOSCH, BLACK&DECKER and KEYANG. Their products were analyzed in terms of product line and product mix concept. Then they are examined by design elements, such as color, shape and material for housing. As an analysis method, the image scale parameter and criteria were applied to each company's product.

• Korean Journal of Labor Studies
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• v.23 no.2
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• pp.109-139
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• 2017

In light that solidarity movements become significant under the situation of 'labor and labor movement' crisis, our study pays attention to the fact that the Hope Bus campaigns made remarkable achievements, and aims to figure out how those campaigns were successful, by focusing on their solidarity networking. The successful operating conditions of solidarity networking in the Hope Bus campaigns are examined in three aspects - the conditions of triggering, forming, and activating. The solidarity networking of Hope Bus campaigns were mainly triggered by the injustice of layoffs by Hanjin Heavy Industry, aerial protest by Jin-sook Kim, and the tragic symbol of the protest site (Crane no. 85). The solidarity movement of Hope Bus could be formed by the mutual trust and cohesive team-building of key network brokers, their utilization and expansion of social movement networks, and massive ripple effect of SNS-mediated communication. The solidarity networking of Hope Bus was effectively activated by open and de-hierarchical operations of the central planning group, active solidarity activities of participant groups, and the provision of 'heuristic experience' for developing the sensibility to labor solidarity. The virtuous combination of those three operating conditions leads to the building of unified forces among social movements, massive civil participation, and meaningful movement outcomes, through the solidarity networking of Hope Bus campaigns.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.394-401
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• 2021

The construction of new renewable energy facilities is steadily increasing every year. In particular, the offshore wind farm market, which has abundant development scalability and a high production coefficient, is growing rapidly. The southwest sea has the highest possible offshore wind power potential, and related projects are to be promoted. This study presents a basic design procedure by the EUROCODE and considers structural safety in the development of an effective of shore wind foundation in the clay layer. In a previous study, the wind power generator of 5MW class was the main target, but the 8MW of wind turbine generator, which meets the technical trend of the wind turbine market in the Southwest sea, was selected as the standard model. Furthermore, a foundation that fulfills the geological conditions of the Southwest sea was developed. The structural safety of this foundation was verified using finite element method. Moreover, structural safety was secured by proper reinforcement from the initial design. Based on the results of this study, structural safety check for various types of foundations is possible in the future. Additionally, specialized structural design and evaluation guidance were also established.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.7
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• pp.1267-1273
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• 2022

Although the Korea shipbuilding industry has recently been receiving most of the orders for ships in the world, production processes are being disrupted due to a shortage of manpower at the production site. This is because the workers quit the shipyard as both work and wages were reduced due to the long slump in the shipbuilding industry. The main reason for the increase in orders was the large-scale orders for Qatar LNG carriers, and the situation in which the technical specifications required for ships are becoming more complex is also working to an advantage. Because the contract delivery time is of utmost importance for ships, the dock launch plan is the most important management item among the shipyard's major processes. The structure to be built in the dock may be a hull that has left the design work or a finished vessel, and in some cases, it is often at the level of some blocks of the hull. When launching, the hull is affected by the hogging or sagging moment due to the fluid force, and securing the safety of the structural strength of the block connection is of utmost importance. In a normal process, the connecting member launches after welding has been completed, but in actual shipbuilders, quick decision-making is needed on the conditions for securing structural safety to comply with the docking schedule. In this study, a detailed analysis method and applicability using a bending stress evaluation method and finite element analysis modelling were analyzed to rationally judge the above-mentioned problems from an engineering point of view. The main contents mentioned in the thesis can be used as good examples when conducting similar structural strength evaluations in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5B
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• pp.469-479
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• 2006

In order to investigate characteristics of the primary flow and the secondary currents in meandering channels, the laboratory experiments were conducted in S-curved channels with angle of bend, $150^{\circ}$, and sinuosity of 1.52. The experimental conditions was decided varying average depth and velocity. Under these experimental conditions, spatial variations of the secondary currents in multiple bends were observed. The experimental results revealed that the distribution of primary flow in straight section is symmetric without respect to the experimental condition and the maximum velocity line of the primary flow occurs along the shortest path in experimental channel, supporting the result of previous works. The secondary currents in second bend became more developed than those in first bend. Particularly, the outer bank cell developed distinctively and the secondary current intensity was low at the straight section and high at the bends, periodically. Also, the secondary current intensity at the bends was as twice to three times as that at the straight section, and has its maximum value at the second bend. The turbulent flow characteristics of meandering channel was investigated with turbulent intensity of the primary flow and Reynolds shear stress. It was observed that the turbulent intensity is increasing when the velocity deviation of the primary flow is large whereas Reynolds shear stress increases when both the velocity deviation of the primary flow and the secondary current are large.