• The Journal of Korean Association of Computer Education
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• v.21 no.6
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• pp.39-47
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• 2018

This paper dealt with investigating the number of minimal spanning ladders originated from ladder game and their properties as well as the related computational thinking aspects. The author modified the filtering techniques to enhance Mathematica project where a new type of graph was generated based on the algorithm using a generator of firstly found minimal spanning graph by repeatedly applying independent ladder operator to a subsequence of ladder sequence. The newly produced YC graphs had recursive and hierarchical graph structures and showed the properties of edge-symmetric. As the computational complexity increased the author divided the whole search space into the each floor of the newly generated minimal spanning graphs for the (5, 10) YC graph and the higher (6, 15) YC graph. It turned out that the computational thinking capabilities such as data visualization, abstraction, and parallel computing with Mathematica contributed to enumerating the new YC graphs in order to investigate their structures and properties.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.4
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• pp.335-342
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• 2019

The objective of this study is to analyze the mechanical properties of plywood used as a thermal insulating material for LNG CCS (Liquefied Natural Gas, Cargo Containment System). It is created by bonding an odd number of parallel and perpendicular direction for preventing contraction and expansion of wood. Also plywood is widely used as LNG CCS insulating material because of its durability, light weight and high stiffness. Since LNG CCS is loaded with liquid cargo, the impact load by sloshing during operation and the wide temperature range (room temperature, low temperature, cryogenic temperature) exposed during loading, unloading should be considered. The thickness of the plywood which is used for the membrane type MARKIII was selected as the thickness of the test specimen. In this present study, plywood is analyzed by the fracture behavior and mechanical properties of plywood by temperature and grain direction. In addition, it is necessary to analyze the fracture shape and predict the fracture strain by using regression model because the critical load may cause cracks inside the tank, which may affect the leakage of cryogenic liquid.

• The Journal of the Petrological Society of Korea
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• v.28 no.3
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• pp.217-225
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• 2019

This study describes a large recumbent fold, which occurs at the north entrance slope of the Batjae tunnel, Pyeongchang-gun, Gangwon-do, and interprets its formation mechanism. The several-hundred-meter scale fold, developed in the Jeongseon Limestone of the Paleozoic Joseon Supergroup, has a nearly horizontal axial plane and its head is facing north. Stretching lineations ($L_1$) observed on the composite foliations of bedding and axial plane cleavage plunge southward at about $10^{\circ}$. Small A-type or eye-shaped sheath folds together with S-shaped asymmetrical folds are often observed in the fold limbs and their axes are nearly parallel to the lineations ($L_1$) within center and rear parts of the fold. It is thus interpreted that the recumbent fold is a large sheath fold produced by the top-to-the-north ductile shearing due to the Songrim orogeny during the late Paleozoic to Triassic.

• The Journal of Engineering Geology
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• v.28 no.4
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• pp.583-592
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• 2018

Recently, concern has arisen regarding the lowering of groundwater levels in the hinterland caused by the development of high-capacity radial collector wells in riverbank filtration areas. In this study, groundwater levels are estimated using Modflow software in relation to the water volume pumped by the radial collector well in Anseongcheon Stream. Using the water volume data, an artificial neural network (ANN) model is developed to determine the amount of water that can be withdrawn while minimizing the reduction of groundwater level. We estimate that increasing the pumping rate of the horizontal well HW-6, which is drilled parallel to the stream direction, is necessary to minimize the reduction of groundwater levels in wells OW-7 and OB-11. We also note that the number of input data and the classification of training and test data affect the results of the ANN model. This type of approach, which supplements ANN modeling with observed data, should contribute to the future groundwater management of hinterland areas.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.10
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• pp.1416-1426
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• 2021

In the case of a scanning type multi-channel LiDAR sensor, the distance error called a walk error may occur due to a difference in received signal power. This work error causes different distance values to be output for the same object when scanning the surrounding environment based on multiple LiDAR sensors. For minimizing walk error in overlapping regions when scanning all directions using multiple sensors, to calibrate distance for each channels using convolution on external system. Four sensors were placed in the center of 6×6 m environment and scanned around. As a result of applying the proposed filtering method, the distance error could be improved by about 68% from average of 0.5125 m to 0.16 m, and the standard deviation could be improved by about 48% from average of 0.0591 to 0.030675.

• Journal of Electrochemical Science and Technology
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• v.12 no.1
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• pp.82-91
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• 2021

This study was conducted to investigate the effect of initial pH, current density, and electrolysis time on process performance in terms of decolorization and chemical oxygen demand (COD) removal from disperse dyebath wastewater (DDW) by mono-polar parallel laboratory scale electrocoagulation (EC) process. COD reduction of 51.3% and decolorization of 92.8% were obtained with operating cost of 0.19 €/㎥ treated wastewater for Al-Al electrode pair, while 90.5% of decolorization and 49.2% of COD reduction were obtained with operating cost of 0.20 €/㎥ treated wastewater for an Fe-Fe electrode pair. The amount of sludge production were highly related to type of the electrode materials. At the optimum conditions, the amount of sludge produced were 0.18 kg/㎥ and 0.28 kg/㎥ for Al-Al and Fe-Fe electrode pairs, respectively. High decolorization can be explained by the hydrophobic nature of the disperse dye, while limited COD removal was observed due to the high dissolved organic matter of the DDW based on auxiliary chemicals. Energy, electrode, and chemical consumptions and sludge handling were considered as major cost items to find a cost-effective and sustainable solution for EC. The contribution of each cost items on operating cost were determined as 10.0%, 51.1%, 30.5% and 8.4% for Al-Al, and they were also determined as 9.0%, 38.0%, 40.5% and 12.5% for Fe-Fe, respectively. COD reduction and decolorization were fitted to first-order kinetic rule.

• English & American cultural studies
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• v.18 no.1
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• pp.1-21
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• 2018

In Woman Watches over the World, Linda Hogan explores the broken identity of herself and her family, the issue of the poverty and the identity crisis, the alcoholism, prevalent in the Native American community and their silenced history. Previous studies have claimed that her memoir contributes to the restoration of Native American identity and history by accusing the violence of white culture, and seeks to recognize a dialogue between native culture and white mainstream culture as well. However they seem to overlook the complicated relations among story, identity, body and nature, to which Hogan as a multi-binded storyteller resorts as a way to break the silence of herself and her tribe for healing. Her own story, as a way to break the silence, becomes the formative drive to reveal the silenced history of her own tribe to lead the young generation to the future. She also understands the formative function of the story, which becomes the vehicle for embodying and connecting themselves to nature. To her, healing lies in the restoration of sympathetic relationship with nature. History, as a type of story, can be made up or mistold just like a story. There may be a blind spot where one can not assess what is true. In spite of the vision of the parallel worlds of the two cultures she presents, there seems to be no immediate solution to the discrimination against the Native American, poverty, identity crisis, and environmental problems which the Native American community faces. However, it can be said that her memoir serves as a rudder by presenting a direction to not only the Native American but also to readers in other cultures in its quest for practical possibilities for the future.

• Journal of the Korean School Mathematics Society
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• v.25 no.2
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• pp.105-124
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• 2022

The contents of fraction division in textbooks are important because there were changes in situations and problem solving methods in textbooks according to the revision of the curriculum and the contents of textbooks affect students' learning directly. So, this study analyzed the achievement standards of the curriculum and formula types and situations, and the introduction process of non-standard and standard algorithms presented in Korean mathematics textbooks. The results are follows: there was little difference in the achievement standards of the curriculum, but there was a difference in the arrangement of contents by grades in textbooks. There was a difference in the types of formula according to textbooks. And the situation became more diverse; recent textbooks have changed to the direction of using the non-standard and the standard algorithm in parallel. In conclusion, I proposed categorizing rather than splitting the types of fraction division, the connection of non-standard and standard algorithm, and the need to prepare methods to pursue generalization and justification according to the common characteristics in the process of introducing standard algorithm.

• Journal of the Korean Orthopaedic Association
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• v.56 no.6
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• pp.540-545
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• 2021

A transverse fracture is the most common type of displaced patella fracture requiring surgery. These fractures are commonly fixed with parallel Kirschner wires or screws that cross the fracture line, often with an additional tension band. Nevertheless, conventional fixation methods of patella fractures have prevalent complications caused by the protrusion of wires or pins. These complications necessitate additional surgery for hardware removal, increase medical cost, and can limit the function of the knee joint. This paper reports cases treated with a minimally invasive load-sharing percutaneous suture of the patella tendon. The procedure provides reliable fixation for transverse patella fractures, minimizes soft tissue injuries, preserves blood flow, and reduces postoperative pain. In addition, the procedure also reduces the irritation and pain caused by the internal fixture, thereby reducing the risk of restricted knee joint movement.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.337-351
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• 2023

In this paper, the shear behavior of soft filling in rectangular-hollow concrete specimens was simulated using the 2D particle flow code (PFC2D). The laboratory-measured properties were used to calibrate some PFC2D micro-properties for modeling the behavior of geo-materials. The dimensions of prepared and modeled samples were 100 mm×100 mm. Some disc type narrow bands were removed from the central part of the model and different lengths of bridge areas (i.e., the distance between internal tips of two joints) with lengths of 30 mm, 50 mm, and 70 mm were produced. Then, the middle of the rectangular hollow was filled with cement material. Three filling sizes with dimensions of 5 mm×5 mm, 10 mm×5 mm, and 15 mm×5 mm were provided for different modeled samples. The parallel bond model was used to calibrate and re-produce these modeled specimens. Therefore, totally, 9 different types of samples were designed for the shear tests in PFC2D. The shear load was gradually applied to the model under a constant loading condition of 3 MPa (σc/3). The loading was continued till shear failure occur in the modeled concrete specimens. It has been shown that both tensile and shear cracks may occur in the fillings. The shear cracks mainly initiated from the crack (joint) tips and coalesced with another one. The shear displacements and shear strengths were both increased as the filling dimensions increased (for the case of a bridge area with a particular fixed length).