• KSCI Review
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• v.8 no.2
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• pp.33-42
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• 2001

The purpose of this study was to help retrieve and assess only what learner wants. The multiple-choice and short-answer types were selected. and a sort of a question bank was organized in consideration of the degree of difficulty and frequency of being questioned in such a way to have a discriminating power. For item retrieval the stored information was converted into XML data, instead of simply searching information from database. and that data were retrieved through Xpath. And it's designed to show the retrieval output by using XML on browser. Concerning item evaluation. evaluation items were produced by inputting the degree of difficulty and frequency of being questioned of the subject and unit learner wants. and then by inputting the number of individual item type. The learning outcome was offered in real time to learner. and learner could repeatedly drill what they gave a wrong answer.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.227-238
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• 1993

IRRI Engineering Division has developed a well drilling rig attachment that matched power tiller or hand tractor. It was designed in response to the growing demand for ground water utilization for small-scale irrigation, especially in drought-sticken and rained farms in Asian countries. The power tiller-driven rig can drill 30 meters of 100mm well in an unconsolidated formation in one day and can be rapidly converted from rotary to jetting or to the percussion method of drilling to suit different soil and rock formation. In addition, the power tiller can be quickly installed or removed from the rig frame and can be used for transporting the rig to other sites. The rig can be dismantled into smaller sub-assemblies for carrying by hand into less accessible areas. One manufacturer in Central luzon Philippines has started to produce the rig for well drillers in Central Luzon. The Department of Agriculture in the Philippines have procured thirty three(33) units of these machines f r their Shallow Tubewell program.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1205-1210
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• 2005

The behavior of rock mass and solute(e.g. groundwater, radioactivity) flow in fractured rock can be directly influenced by joint roughness. The characteristics of joint roughness is also a main factor for the rock classification(e.g. RMR, Q system) which is usually used in tunnel design. Nevertheless, most of JRC estimation has been carried out only by the examination with the naked eye. This JRC estimation has a lack of objectivity because each investigator judges JRC by his subjective opinion. Therefore, it will be desirable that the assessment of JRC is performed by a numerical analysis which can give a quantitative value corresponding to the characteristics of a roughness curve. Meanwhile, roughness curves for joint surfaces which are observed in drill cores have been obtained only along linear profiles. Although roughness curves are measured in the same joint surface, they can frequently show diverse aspects in a standpoint of roughness characteristics. If roughness curves can be measured along the elliptical circumferences of joint surfaces from core scanning images or Televiewer images, they will certainly be more comprehensive than those measured along linear profiles for roughness characteristics of joint surfaces. This study is focus on dealing with (1) extracting automatically roughness curves from core scan image or Televiewer image, (2) improving the accuracy of quantitative assessment of JRC using fractal dimension concept.

• Child Health Nursing Research
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• v.22 no.2
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• pp.117-125
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• 2016

Purpose: This study was done to examine the effect of direct practice of newborn health assessment on nursing student's clinical competence and self-efficacy and to propose effective strategies for clinical education on newborn care. Methods: Design was a nonequivalent control group quasi-experimental study. The direct practice program was composed of a lecture, demonstration, drill and feedback using a manikin, and repeated direct practice regarding newborn health assessment. Participants were 65 student nurses taking the pediatric nursing practicum in the nursery room at M hospital. The experimental group (n=33) participated in the direct practice program for newborn health assessment and the control group (n=32) received the traditional practice method. Nursing clinical competence was assessed by two nurse investigators and structured questionnaires were used to measure self-efficacy. Results: The experimental group's clinical competence was significantly higher than that of the control group (t=-4.82, p=.000). However no significant difference was found between the two groups for self-efficacy (t=1.264, p=.211). Conclusion: These findings indicate that the direct practice program is effective in improving nursing student's clinical competence, but it was not effective in increasing self-efficacy. Direct practice in various clinical education settings is recommended and longitudinal effects be evaluated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.160-166
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• 2015

Ultrasonic machining (USM) has been considered a new, cutting-edge technology that presents no heating or electrochemical effects, with low surface damage and small residual stresses on brittle workpieces. However, nowadays, many researchers are paying careful attention to the disadvantages of USM, such as low productivity and tool wear. On the other hand, in this study, a high-performance rotary ultrasonic drilling (RUD) spindle is designed and assembled. In this system, the core technology is the design of an ultrasonic vibration horn for the spindle using finite element analysis (FEA). The maximum spindle speed of RUM is 9,600 rpm, and the highest harmonic displacement is $5.4{\mu}m$ noted at the frequency of 40 kHz. Through various drilling experiments on glass workpieces using a CVD diamond-coated drill, the cutting force and cracking of the hole entrance and exit side in the glass have been greatly reduced by this system.

• Geomechanics and Engineering
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• v.19 no.1
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• pp.93-104
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• 2019

Anomalies and/or fractured grounds not detected by the surface geophysical and geological survey performed during design stage may cause significant problems during tunnel excavation. Many studies on prediction methods of the ground condition ahead of the tunnel face have been conducted and applied in tunneling construction sites, such as tunnel seismic profiling and probe drilling. However, most such applications have focused on the drill and blast tunneling method. Few studies have been conducted for mechanized tunneling because of the limitation in the available space to perform prediction tests. This study aims to predict the ground condition ahead of the tunnel face in TBM tunneling by using an electrical resistivity tomography survey. It compared the characteristics of each electrode array and performed an investigation on in-situ tunnel boring machine TBM construction site environments. Numerical simulations for each electrode array were performed, to determine the proper electrode array to predict anomalies ahead of the tunnel face. The results showed that the modified dipole-dipole array is, compared to other arrays, the best for predicting the location and condition of an anomaly. As the borehole becomes longer, the measured data increase accordingly. Therefore, longer boreholes allow a more accurate prediction of the location and status of anomalies and complex grounds.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.115-127
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• 2019

The low-flow grouting injection technique, the target construction method for this study, is a method of pouring mortar into the ground by non-emission replacement principle, which can be expected to increase the density of the ground, and, in some cases, be used as a base file using the strength of the high injection solids, along with low noise, low pollution, and high durability. To verify that the dynamic characteristics of the ground are improved by the low-flow injection technique, the test work was conducted on the site and physical tests were performed, and the quality of the improvement formed in the ground was verified through the indoor test on the core and core recovery rate was analyzed. The density logs test layer calculated the volume density of the ground layer by using the Compton scattering of gamma-rays, and the sonic logs was tested on the ground around the drill hole using a detector consisting of sonar and receiver devices inside the drill hole. As a result of the measurement of the change in physical properties (density and sonic logs) before and after grouting, both properties were basically increased after infusion of grout agent. However, the variation in density increase was greater than the increase in speed after grouting, and the ground density measurement method was thought to be effective in measuring the fill effect of the filler. Strength and core recovery rates were measured from specimens taken after the age of 28 days, and the results of the test results of the diffusion and strength test of the improved products were verified to satisfy the design criteria, thereby satisfying the seismic performance reinforcement.

• The KIPS Transactions:PartA
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• v.12A no.5 s.95
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• pp.461-470
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• 2005

In leaner-controlled environment where learners can decide and restructure the contents, methods and order of learning by themselves, it is possible to apply individualized learning in consideration of each learner's characteristics. The present study analyzed learners' learning path pattern, which is one of learners' characteristics important in Web-based teaching-learning process, using the Apriori algorithm and grouped learners according to their learning path pattern. Based on the result, we designed and implemented a multi-dimensional learning path pattern analysis system to provide individual learners with teaming paths, learning contents, learning media, supplementary teaming contents, the pattern of material presentation, etc. multi-dimensionally. According to the result of surveying satisfaction with the developed system satisfaction with supplementary learning contents was highest (Highly satisfied '$24.5\%$, Satisfied'$35.7\%$). By learners' level, satisfaction was higher in low-level learners (Highly satisfied'$20.2\%$, Satisfied'$31.2\%$) than in high-level learners (Highly satisfied'$18.4\%$, 'Satisfied'$28.54\%$). The developed system is expected to provide learners with multi-dimensionally meaningful information from various angles using OLAP technologies such as drill-up and drill-down.

• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.3
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• pp.155-170
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• 2010

Availability of economic and efficient energy resources is crucial to a nation's development. Because of their low cost and advancement in drilling and exploration technologies, oil and gas based energy systems are the most widely used energy source throughout the world. The inexpensive oil and gas based energy systems are used for everything, i.e., from transportation of goods and people to the harvesting of crops for food. As the energy demand continues to rise, there is strong need for inexpensive energy solutions. An offshore platform is a large structure that is used to house workers and machinery needed to drill wells in the ocean bed, extract oil and/or natural gas, process the produced fluids, and ship or pipe them to shore. Depending on the circumstances, the offshore platform can be fixed (to the ocean floor) or can consist of an artificial island or can float. Semi-submersibles are used for various purposes in offshore and marine engineering, e.g. crane vessels, drilling vessels, tourist vessels, production platforms and accommodation facilities, etc. The challenges of deepwater drilling have further motivated the researchers to design optimum choices for semi-submersibles for a chosen operating depth. In our series of eight papers, we discuss the design and production aspects of all the types of offshore platforms. In the present part I, we present an introduction and critical analysis of semi-submersibles.

• Explosives and Blasting
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• v.23 no.4
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• pp.1-18
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• 2005

The underground research tunnel, which is under construction in KAERI for the validation of HLW disposal system, is excavated in a granite rock by drill&blasting. In order not to disturb the operation at the research facilities including Hanara reactor by the blasting for the excavation of $6m{\times}6m$ tunnel, a test blasting at the site was performed. Using the vibration equation derived from the test blasting, it was possible to predict the vibration at different locations at KAERI and to conclude that the blasting design would meet the design criteria at the major facilities in KAERI. The noise and vibration generated by the main blasting were continuously measured. In the case of vibration, the measured values were lower than the predicted one from the vibration equation. It is, therefore, concluded that the influence of blasting work for the construction of 280m long research tunnel on the major facilities in KAERIl would be insignificant.