• Journal of the Korea Society of Computer and Information
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• v.4 no.3
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• pp.1-7
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• 1999

This study is to design and implement the synthetic courseware that covers repeating learning, individual teaching, and effective teaching-learning games by using multimedia authoring tool KAS for numerical data of computer science which is especially a little boring and difficult to understand through blackboard-based lesson for senior high school students. It also overcomes the drawbacks of the existing CAI focused on text and image by combining various kinds of media like image, animation and sound effects. Animation of numerical data in the fields of radix conversion makes it possible for learners to check the individual learning process and visual interest. So it comes to increase the effectiveness of learning. Whenever each chapter is finished. learners' understanding can be evaluated by formative test. Applicability test of the developed CAI in Eumsung Senior High School. is statistically evaluated as more effective than that of the blackboard-based lesson.

• Journal of the Korean GEO-environmental Society
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• v.18 no.9
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• pp.11-18
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• 2017

Numerical analysis method for prediction of pile behaviour characteristics has widely been used in detail design process before construction because field static loading test requires high cost. However, the reliability verification of numerical analysis of result is not permitted compare with field test. In this study, to verify the numerical analysis results, pile behaviour prediction was compared with field static loading test results. For exact analysis of interaction between pile and ground, soil investigation and in-situ test such as boring, SPT and bore-hole shear test were performed before pile static loading test. During the static loading test, pile behaviour characteristics were analyzed under every loading condition. After static pile loading test, numerical analysis was carried out under same condition with static pile loading test. In the numerical analysis, to apply same loading condition with each loading condition in the field test and to compare with between the results of numerical analysis, the field test results for reliability were verified with the results of numerical analysis.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.219-237
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• 2020

Rapid economic development and urban population growth have been increasing the necessity for underground space exploration and utilization due to the need of upgrading and expanding the existing infrastructures. TBM has been widely used to construct underground structures with high advance rate and minimal ground disturbance. Two important design parameters, which are available thrust capacity and cutterhead torque, should be estimated for any project in addition to proper selection of TBM type. However, the conventional thrust force and torque estimation model only depends on the empirical equation, which hinders the design process of the optimal thrust hydraulic system and the appropriate hydraulic components. In this study, four thrust and torque calculation models are derived and explained. For TBM design practice, the four estimation models are compared and discussed.

• FLOWER RESEARCH JOURNAL
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• v.17 no.3
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• pp.214-219
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• 2009

The current study was based on a survey of 429 middle school students (202 male and 227 female students) who lived in Ansan City. Most students (74%) had an experience in horticultural activities during or after elementary school years (male 43%, female 41%). Middle school students answered that they most frequently learned about growing up vegetables and plants among horticultural activities (male 73%, female 79%) and they thought horticultural activities are very important for education purpose such as environmental education. The most preferred horticultural activities program was utilizing vegetables and plants of which students generally had no experiences. That male students (46%) answered that the most interested aspect of horticultural activities in growth process of vegetables and plants while female answered (36%) the importance of plant life. However the most unfavorite aspect of horticultural activities was the time-consuming as a 58%, and then boring (33%).

• 한국노년학
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• v.38 no.3
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• pp.607-625
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• 2018

This study is on mid-seventies female gamblers who went through Korean modern history. The purpose is to analyze interviews on their life of understanding what their true self is, and to redefine gambling. The concept of 'existential self-regulation' was proposed and the materials were acquired through narrative interviews. The materials were then investigated according to Mandelbaum's framework for analysis of which suggests dimension, turning, and adaptation. The self-narrative revealed that the process of being addicted to gambling is as in the following: compensating her emotional deficiency via money and child's education, getting rid of the emotional deficiency via gambling, becoming free from emotional deficiency. The meaning of gambling has shifted to a comfort to existential vacuum, a source of anxiety ruining life, pastime for boring everyday life. Life events that control the impulse to gamble through 'existential self-knowledge' occurred in the second and the third stage. Based on the results, the study suggests mid-seventies female gamblers to write her autobiography, and proposed the necessity of self-examining programs.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1039-1048
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• 2018

In urban tunnel construction, most of the Shield TBM method is applied to secure the safety of buildings and to minimize risks. On the other hand, in the urban development process, landfills are often embanked or improving in many cases, so that the boundary between the surface and the rock is often heterogeneous. In case of ground condition such as alluvial soil, granite, decomposed granite, core stone and rock with various layers, datas on shield TBM advancing according to each ground condition are analyzed, The characteristics of machine load were compared and analyzed. As a result, it can be predicted that the change of ground condition can be predicted by the tendency of discharge volume, thrust force and cutting wheel torque when the cutter is checked and replaced regularly on advancing under maintaining the design slurry pressure.

• Tunnel and Underground Space
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• v.33 no.4
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• pp.244-254
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• 2023

The disc cutter mounted on the Tunnel Boring Machine (TBM) is subjected to cutting forces in three dimensions during rock excavation process. It is widely known that the cutting forces increased with the strength of the rock mass, while the rolling force can be significantly increased when the disc cutter encounters abnormal rotation. Therefore, the cutting force acts on the disc cutter provides important information because it represents the conditions of the rock mass and the disc cutter. For these reasons, several studies have been conducted to measure the cutter forces in real-time. This paper introduces the current status of research on the cutter force measurement of TBM disc cutters, which has been reported in the literature. It is judged that this paper can be a useful reference material when similar technologies are developed in Korea in the future.

• Geomechanics and Engineering
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• v.34 no.1
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• pp.103-113
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• 2023

This study focused on understanding the relationship between the design of a tunnel boring machine disc cutter ring and its rock-breaking efficiency, as well as the applicable conditions of different cutter ring types. The discrete element method was used to establish a numerical model of the rock-breaking process using disc cutters with different ring types to reveal the development of rock damage cracks and variation in cutter penetration load. The calculation results indicate that a sharp-edged (V-shaped) disc cutter penetrates a rock mass to a given depth with the lowest load, resulting in more intermediate cracks and few lateral cracks, which leads to difficulty in crack combination. Furthermore, the poor wear resistance of a conventional V-shaped cutter can lead to an exponential increase in the penetration load after cutter ring wear. In contrast, constant-cross-section (CCS) disc cutters have the highest quantity of crack extensions after penetrating rock, but also require the highest penetration loads. An arch-edged (U-shaped) disc cutter is more moderate than the aforementioned types with sufficient intermediate and lateral crack propagation after cutting into rock under a suitable penetration load. Additionally, we found that the cutter ring wedge angle and edge width heavily influence cutter rock-breaking efficiency and that a disc cutter with a 16 to 22 mm edge width and 20° to 30° wedge angle exhibits high performance. Compared to V-shaped and U-shaped cutters, the CCS cutter is more suitable for soft or medium-strength rocks, where the penetration load is relatively small. Additionally, two typical case studies were selected to verify that replacing a CCS cutter with a U-shaped or optimized V-shaped disc cutter can increase cutting efficiency when encountering hard rocks.

• Tunnel and Underground Space
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• v.34 no.2
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• pp.154-168
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• 2024

The Tunnel Boring Machine (TBM) disc cutter is subjected to wear and damage during the rock excavation process, and the worn disc cutter should be replaced on time. The manual inspection by workers is generally required to determine the disc cutter replacement. In this case, the workers are exposed to dangerous environments, and the measurements are sometimes inaccurate. In this study, we developed a technology that measures the disc cutter wear in real time. From a series of laboratory tests, a magnetic sensor was selected as the wear sensor, and the real-time disc cutter measurement system was developed integrating wireless communication modules, power supply and data processing board. In addition, the measurement system was verified in actual TBM excavation circumstances. As a result, it was confirmed that the accuracy and stability of the system.

• Journal of the Korean Society of Tobacco Science
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• v.1 no.1
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• pp.56-62
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• 1979

Boring the process of curing of the tobacco ( Nicotiana tabacum L. clicks) leaf, the and other fundamental components of the tobacco leaf was observed The amount of total chlorophyll was reduced from 2902$\mu\textrm{g}$/gr to 1, 131$\mu\textrm{g}$/gr as a function of curing time. In the case of total carotene, the concentration was increased from 373-712$\mu\textrm{g}$/gr. to 3, 003~2, 215$\mu\textrm{g}$/gr. up to 70 hours of curing period. However, after 70 hours of curing, the concentration of total carotene stared to be decreased up to 1, 050~1, 039$\mu\textrm{g}$/gr. Simultaneously, the greenish yellow color becomes to be close an intermediate color between yellow and orange. The amount of total nicotine and nitrogen (2~2%) in the green harvested leaf was essentially identical after the curing process. However, the amount of total sugar was enhanced from 17%, in the green harvested leaf, to 35% at the time of 70 hours curing. At the end of the curing, the amount of total sugar was again reduced up to 16%. The correlation coefficient (r) between the axis of the color coordinate and the ratio of chlorophyll/carotene was estimated to be r=-0.96. This result indicates a linear relationship between those two parameters and the following linear equation is obtained as y=28.87-68.38 x. From the above equation, x=0.442 could be estimated when chlorophyll was completely decomposed (ylongrightarrowO). As a consequence of this result, we can suggest the tobacco leaf of Hicks belongs to the high quality level.