• Journal of the Society of Naval Architects of Korea
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• v.56 no.3
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• pp.251-262
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• 2019

This paper is about design concept and simplified analysis method against dropped object events. The ships and offshore structures are exposed to various types of dropped object accidents such as laydown area struck by drill collar and topside deck hit by food container during their lifetime. Mitigation can be accomplished by proper facility layout and designing structures to safely absorb energy from accidental loads. It shall be designed to avoid loss of life, environmental pollution and loss of assets. Impact loads can lead to structural global collapse of the main structure or punching of a local barrier type structure with potential to escalate directly or indirectly to a global collapse of the structure. This study provides the background information on the issue of dropped object of the shipyard and also focuses on structural assessment of the local individual component such as deck plate, stiffener and web/girder by using simplified analysis method. The results of the simplified analysis method were compared with numerical results using non-linear finite element simulation.

• 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.

• International Journal of Contents
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• v.7 no.3
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• pp.13-18
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• 2011

Oriental medicine statistics are essential in research planning, research evaluation, and policy decision based on objective data. However, integrated administration of such statistics is not presently possible in the oriental medicine field, which has been slow in incorporating information communication technology. In an effort to address this problem, the Korea Institute of Oriental Medicine (KIOM) developed an oriental medicine statistical system in 2009, and the system has been offered in the traditional medicine information portal of OASIS. However, according to a 2010 survey targeting OASIS users, those surveys reported that needs for a system where various statistical data can be extracted via an interactive approach to multidimensional data. As a result of an analysis of the functions of the existing system, it was found that it is necessary to array and arithmetically analyze Stats Value, Drill Up & Drill Down, and Pivot. To this end, the existing DB schema should be redesigned. Based on our analysis result, we redesigned the database into a structure that is applicable to the reverse pivot algorithm. We used J2EE/JSP and a Flex framework to design and develop an oriental medicine statistical system that can provide multidimensional statistical data. Considering that the improved oriental medicine statistical system is planned to be offered by OASIS of KIOM, utilization and value of oriental medicine statistical data are expected to be enhanced.

• Geomechanics and Engineering
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• v.31 no.3
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• pp.249-263
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• 2022

The specially-shaped Polycrystalline Diamond Compact (PDC) cutter is widely used in drill bit design due to its advantages of high rock cutting efficiency, strong impact resistance and long service life in hard and abrasive formation drilling. A detailed understanding of rock cutting behavior of worn specially-shaped PDC cutter is essential to improve the drilling efficiency and decrease the drilling costs. In this paper, the theoretical models of two new principles (loading performance (LP) and cutting performance (CP)) are derived for evaluating the cutting process of worn specially-shaped cutter, the theoretical models consider the factors, such as cutter geometry, aggressiveness, stress state, working life, and rock cutting efficiency. Besides, the numerical model of heterogeneous granite is developed using finite element method combined with Voronoi tessellation, the LP and CP of 12 kinds of worn specially-shaped PDC (SPDC) cutters are analyzed. The results found that the mechanical specific energy (MSE) of worn cutters first increase and then decrease with increasing the cutting depth, and the MSE increase with the increase of back rake angle except for Conical cutter and Wedge-shaped cutter. From the perspective of CP, the worn PDC cutters are more suitable for the smaller cutting depths, and the back rake angle has little effect on the CP of the specially-shaped worn PDC cutters. Conical cutter, Saddle-shaped cutter and Ellipse-shaped cutter have the highest CP value, while Rhombus-shaped cutter, Convex cutter and Wedge-shaped cutter have the lowest value in selecting cutters. This research leads to an enhanced understanding of rock-breaking mechanisms of worn SPDC cutters, and provides the basis to select of specially-shaped PDC cutters for the specific target formation.

• Korean Journal of Human Ecology
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• v.11 no.4
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• pp.381-389
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• 2002

This research was designed to investigate the preference to textiles for slacks of college students. 105 subjects majored in fashion design were surveyed. Subjects selected three favorite materials among 120 samples presented in swatch book and weighted frequency and percentage were added by order. The extent of preference was compared by season and sex. The results of this study were as follows: 1. College students preferred twill cotton Drill foremost as a textile for spring and fall season. 2. Plain linen Crash was the most preferred material for summer. 3. Cotton Corduroy was the most preferred textile for winter. 4. In thickness and weight, textiles for winter were thicker and heavier than those of other seasons. 5. In fiber content, natural fiber such as wool were preferred for all seasons. 6. In weave of textiles, twill weave fabric was preferred for spring fall and winter season, and plain weave for summer. 7. College students preferred plain texture materials foremost and navy blue and black color was preferred for textiles for slacks. 8. Girl students preferred cotton fabrics and boys preferred wool fabric for slacks. Also, girls generally preferred thinner fabrics than those of boys.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.4 s.181
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• pp.29-36
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• 2006

Micro drilling by high-speed air bearing spindle is very useful manufacturing technology in electronic industry For the design of high speed air bearing spindle, there are considered stability of air bearing spindle, allowable load of air bearing, run out and tooling system design for micro drill's attach and remove. According to suggested details, we designed and manufactured high-speed air bearing spindle and carried out performance estimation such as run out, temperature change in running air bearing spindle, stiffness, chucking torque. Results are follows; Run out was measured under $5{\mu}m$ at air bearing spindle revolution $20,000\sim125,000rpm$. High speed air bearing spindle's temperature rose about $20^{\circ}C$ after 5 minutes from running and then was fixed. Allowable thrust load of spindle was 17kgf. Chucking torque of collet was 15kgfcm.

• Journal of The Korean Association For Science Education
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• v.14 no.1
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• pp.24-33
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• 1994

This study is aimed at categorizing the CAl programs through analyzing the 82 science CAl programs developed by KEDI( Korean Educational Development Institutes ) and the 19 science CAl programs developed by the teachers who won the prizes in the first national educational software contest. The findings are as follows. 1) The main types of science CAl programs developed by KEDI are hybrid design type of tutorials and simulations, tutorials, and hybrid design type of instructional games and drill and practice. The other type of programs are very few. 2) The main types of science CAl programs developed by the teachers, who won the prizes in 1st educational software contest, are tutorials and hybrid design type of tutorials and simulations. There is no other type of programs except only two simulation type programs. 3) The science CAl programs developed by KEDI as well as by teachers who won the prizes in the contest are biased in two or three types, and the trend is severe in the programs developed by the teachers.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.5
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• pp.431-449
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• 2022

As many tunnels generally have been constructed, various experiences and techniques have been accumulated for tunnel design as well as tunnel construction. Hence, there are not a few cases that, for some usual tunnel design works, it is sufficient to perform the design by only modifying or supplementing previous similar design cases unless a tunnel has a unique structure or in geological conditions. In particular, for a tunnel blast design, it is reasonable to refer to previous similar design cases because the blast design in the stage of design is a preliminary design, considering that it is general to perform additional blast design through test blasts prior to the start of tunnel excavation. Meanwhile, entering the industry 4.0 era, artificial intelligence (AI) of which availability is surging across whole industry sector is broadly utilized to tunnel and blasting. For a drill and blast tunnel, AI is mainly applied for the estimation of blast vibration and rock mass classification, etc. however, there are few cases where it is applied to blast pattern design. Thus, this study attempts to automate tunnel blast design by means of machine learning, a branch of artificial intelligence. For this, the data related to a blast design was collected from 25 tunnel design reports for learning as well as 2 additional reports for the test, and from which 4 design parameters, i.e., rock mass class, road type and cross sectional area of upper section as well as bench section as input data as well as16 design elements, i.e., blast cut type, specific charge, the number of drill holes, and spacing and burden for each blast hole group, etc. as output. Based on this design data, three machine learning models, i.e., XGBoost, ANN, SVM, were tested and XGBoost was chosen as the best model and the results show a generally similar trend to an actual design when assumed design parameters were input. It is not enough yet to perform the whole blast design using the results from this study, however, it is planned that additional studies will be carried out to make it possible to put it to practical use after collecting more sufficient blast design data and supplementing detailed machine learning processes.

• Journal of the Korea Society for Simulation
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• v.27 no.2
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• pp.11-24
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• 2018

The purpose of the present study is to develop an analysis model to analyze the design parameter sensitivity of a high-power drifter suitable for implementation in Korean hydraulic drills. This study aims to establish a basis for the optimization of the impact performance and stability of a high-power drifter by investigating the effects of each design parameter on the impact performance via design parameter sensitivity analysis. To begin, an analysis model of drifter dynamics is developed, and the reliability of the analysis model is verified by comparing the analysis results to the experimental results. The drifter is then redesigned for compatibility with Korean hydraulic drills. Finally, design parameter sensitivity analysis of the redesigned drifter is conducted to determine the effects of the design parameters on the impact performance, and to extract the high-sensitivity parameters. SimulationX, which is multi-physics analysis software, is used to develop the analysis model, and EasyDesign is employed for design parameter sensitivity analysis.

• Journal of KSNVE
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• v.10 no.2
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• pp.299-305
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• 2000

In this study, the characteristics of transmitted vibration on hand-arm system are examined when operating electric hand tools. Also through the correlation analysis between anthroponetric data and transmitted vibration, and comparison study with appropriate amount of work done based on the ISO criteriaa, the basic data for the ergonomic work design can be presented. The types of electric tools and works for the experiment are drill (general type and impact type), grinder, wire brush and steel to analyze the characteristics of transmitted vibrations, the amount of transmitted vibrations in X, Y and Z direction at tool(T), hand(H), wrist(W), and the joint between foream and upper arm(A) were measured at the frequency range of 6.3∼1000[HZ]. Also, the limit of human exposure to vibration, and the response of frequency were conducted.