• Journal of Powder Materials
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• v.25 no.6
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• pp.475-481
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• 2018

Selective laser melting (SLM), a type of additive manufacturing (AM) technology, leads a global manufacturing trend by enabling the design of geometrically complex products with topology optimization for optimized performance. Using this method, three-dimensional (3D) computer-aided design (CAD) data components can be built up directly in a layer-by-layer fashion using a high-energy laser beam for the selective melting and rapid solidification of thin layers of metallic powders. Although there are considerable expectations that this novel process will overcome many traditional manufacturing process limits, some issues still exist in applying the SLM process to diverse metallic materials, particularly regarding the formation of porosity. This is a major processing-induced phenomenon, and frequently observed in almost all SLM-processed metallic components. In this study, we investigate the mechanical anisotropy of SLM-produced 316L stainless steel based on microstructural factors and highly-oriented porosity. Tensile tests are performed to investigate the microstructure and porosity effects on mechanical anisotropy in terms of both strength and ductility.

• Korean Journal of Metals and Materials
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• v.46 no.12
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• pp.788-799
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• 2008

This study is concerned with the effects of Mo, Cr, and V addition on tensile and Charpy impact properties of API X80 linepipe steels. Four kinds of steels were processed by varying Mo, Cr, and V additions, and their microstructures and tensile and Charpy impact properties were investigated. Since the addition of Mo and V promoted to form fine acicular ferrite and granular bainite, while prohibiting the coarsening of granular bainite, it increased the strength and upper shelf energy, and decreased the energy transition temperature. The Cr addition promoted the formation of coarse granular bainite and secondary phases such as martensite-austenite constituents, thereby leading to the increased effective grain size, energy transition temperature, and strength and to the decreased upper shelf energy. The steel containing 0.3wt.% Mo and 0.06wt.% V without Cr had the highest upper shelf energy and the lowest energy transition temperature because its microstructure was composed of fine acicular ferrite and granular bainite, together with a small amount of hard secondary phases, while its tensile properties maintained excellent.

• The Journal of the Korea Contents Association
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• v.21 no.1
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• pp.561-571
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• 2021

The 2017 Pohang earthquake left us with issues related to long-term repair and restoration from massive earthquake damage. The existing Earthquake response manual was insufficient to consider the flow of earthquake disaster work and the characteristics of long-lasting earthquake disaster. Accordingly, It is important to analyze and record how to earthquake response work was carried out during the Pohang earthquake. The functions that require the most work and manpower in the event of an earthquake disaster were emergency life stabilization support, facility emergency recovery, and energy functional restoration. As a result of analyzing the difficulties and problems of disaster response by function, it was found that the prevention and preparation for damage in advance was insufficient for each function. In conclusion, we subdivided the response step applied with the concept of time and presented the overall work flow process for thirteen collaboration functions. It is expected that this result will help disaster managers to work effectively in the event of a large scale earthquake.

• Journal of Korean Foot and Ankle Society
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• v.25 no.4
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• pp.165-170
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• 2021

Purpose: This study sought to evaluate the clinical effectiveness of the shortening effect of the modified Weil osteotomy for the treatment of Freiberg's disease. Materials and Methods: We reviewed 21 cases treated with the modified Weil osteotomy for Freiberg's disease from November 2005 to June 2019. The average follow-up period was 32.5 months and the mean age of the patients was 38.3 years. The clinical results were analyzed using the American Orthopaedic Foot and Ankle Society (AOFAS) lesser metatarsophalangeal-interphalangeal scale, the visual analogue scale (VAS), and the range of motion (ROM) of the metatarsophalangeal joint. In the radiologic evaluation, the length of preoperative and postoperative metatarsal shortening was compared. Results: The average AOFAS lesser metatarsophalangeal-interphalangeal scale showed an improvement from 60.5 preoperatively to 90.9 at the latest follow-up. VAS showed a decrease from 5.4 preoperatively to 0.9 at the latest follow-up. ROM of the affected metatarsophalangeal joint increased from 40.2 degrees preoperatively to 58.6 degrees at the latest follow-up. The mean length of metatarsal shortening was 6.7 mm. There was no transfer metatarsalgia, osteonecrosis, and definite joint space narrowing. Conclusion: Modified Weil osteotomy with second layer cutting is an effective treatment option to restore the joint surface and painless joint motion for patients with Freiberg's disease.

• Journal of Korea Port Economic Association
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• v.38 no.1
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• pp.73-86
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• 2022

This study aims at investigating measures to vitalize the Pohang Yeongil New Port and its hinterland in the context of the post Covid-19 pandemic. To identify appropriate strategies, an SWOT analysis combined with fuzzy-AHP(Analytic Hierarchy Process) was applied for strategical priority. Among the SWOT factors, weaknesses and threats were found to be critical. At a more detailed level, the strategic priorities were given to insufficient infrastructure (W), neighboring ports (T), insufficient shipping network (W), low service level (W) and South-North Korea relationships (T). Given these results, several strategies to overcome core weaknesses and threats of the Pohang Yeongil Port were suggested. The results of this study may provide valuable insights for port policy makers.

• Composites Research
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• v.19 no.6
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• pp.23-31
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• 2006

We measured mechanical properties, including Young's modulus, effective bending modulus and nominal fracture strength of nanohoneycomb structures using an Atomic Force Microscope(AFM) and a Nano-Universal Testing Machine(UTM). Anodic aluminum oxide(AAO) films are well suited as nanohoneycomb structures because of the simple fabrication process, high aspect ratio, self-ordered hexagonal pore structure, and simple control of pore dimensions. Bending tests were carried out for cantilever structures by pressing AFM tips, and the results were compared with three-point bending tests and tensile tests using a Nano-UTM. One side of the AAO films is clogged by harrier layers, and looks like a face material of conventional sandwich structures. Analysis of this layer showed that it did not influence the bending rigidity, and was just a crack tip. The present results can act as a design guideline in applications of nanohoneycomb structures.

• Journal of Science and Technology Studies
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• v.18 no.2
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• pp.269-306
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• 2018

Through this study, it is aimed to derive the policy direction considering the characteristics of the present Smart Factory, the industrial condition of Pohang area, and the promotion field. Secondly, the questionnaire data of the regional enterprises will prepare for the improvement of the industrial structure and the implications for efficiency, and preparation for regional preparation and industrial changes in preparation for the next generation of production revolution. The construction of Smart Factory in Pohang can be divided into two major directions. First, it is analyzed that smart factory pilot projects are highly needed, focusing on competitive medical precision manufacturing field among the SMEs in the region, primary metal and nonmetal manufacturing industries, and other machinery fields. In addition, local SMEs are willing to introduce smart factories for reasons of quality improvement and cost reduction, and it is confirmed that they will actively promote employee training and expertise if they can upgrade continuously.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.111-116
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• 2005

The approaching waters of Po-hang port will be increased the traffic volume and passage of larger vessel according to the opening of Young-il new port in 2006. But the adjacent area of Po-hang port still exist the danger elements of safe navigation, the disordered navigation and traffic congestion. Therefore the safety of traffic must be improved in Po-hang vicinity area. This paper describes the status of marine traffic flow and navigational characteristics based on the marine traffic survey using the exclusive software, and the results of marine traffic survey classify into the ship's types and tonnage and track history of passing ships through the statistical method. Finally the examinations of main traffic route, traffic flow and navigational characteristics are discussed, and these results can be utilized the best design of ship's routing at the Po-hang approaching water.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.235-258
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• 2022

We interpreted the evolutionary history of the southwestern part of the Pohang Basin, the largest Miocene basin in the southeastern part of the Korean Peninsula, based on the detailed geological mapping and analysis of the geological structures. The southwestern part of the Pohang Basin can be divided into the Bomun Domain in the west and Ocheon Domain in the east by an NNE-trending horst-in-graben. These two domains have different geometries and deformation histories. The Bomun Domain was rarely deformed after the incipient extension of the basin, whereas the Ocheon Domain is an area where continued and overlapped deformations occurred after the basin fill deposition. Therefore, the Bomun Domain provides critical information on the initial extension mode of the Pohang Basin. The subsidence of the Bomun Domain was led by the zigzag-shaped western border fault that consists of NNE-striking normal and NNW-striking dextral strike-slip fault segments. This border fault is connected to the Yeonil Tectonic Line (YTL), a regional dextral principal displacement zone and the westernmost limit of Miocene crustal deformation in SE Korea. Therefore, it is interpreted that the Pohang Basin was initially extended in WNW-ESE direction as a transtensional fault-termination basin resulting from the movement of NNE-striking normal and/or oblique-slip faults formed as right-stepover in the northern termination of the YTL activated since approximately 17-16.5 Ma. As a result, an NNE-trending asymmetric graben or half-graben exhibiting an westward deepening of basin depth was formed in the Bomun Domain. Afterward, crustal extension and deformation were migrated to the east, including the Ocheon Domain.

• Journal of Science and Technology Studies
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• v.19 no.3
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• pp.51-117
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• 2019

On 15th November 2017, the coastal city of Pohang, located in the Southeastern part of South Korea was shaken by a magnitude 5.4 earthquake. The earthquake displaced more than 1,700 residents and caused more than $ 300 million dollars of economic loss. It was the second most damaging earthquake in the history of Korea. Soon after the earthquake, a group of scientists raised a possible link between the first Enhanced Geothermal System (EGS) project and the earthquake. At the same time, another group of scientists put forward a different hypothesis of the causation of the earthquake claiming that it was caused by the geological movements that were initiated by the Great Tohoku Earthquake in 2011. Since then, there were scientific debates between the two different groups of scientists. The scientific debate on the causation of the earthquake has been concluded temporarily by the Research Investigatory Committee on the Pohang Earthquake in 2019. The research committee concluded that the earthquake was caused by the Pohang EGS system: this means that the earthquake can be defined not as a natural earthquake, but as an artificially triggered earthquake. This article is to examine the Pohang earthquake can be defined as an Anthropocenic event. The newly suggested concept, the Anthropocene is a relatively novel term to classify the earthly strata and their relationship to geological time. The current geological period should be defined by human activities and man-made earthly environment. Although the term is basically related to geological classification, the Anthropocene has been widely debated amongst humanist and social science scholars. The current disastrous situation of our planet also implies with the Anthropocene. This paper is to discuss how to understand anthropogenic events. In particular, the paper pays attention to two different scholarly positions on the Anthropocene: Isabelle Stenger's Gaia theory and Barbara Herrnstein Smith's relativist theory. The former focuses on the earthly inevitable catastrophe of Anthropocene while the latter suggests to situate and contextualise anthropogenic events. On the basis of the theoretical positions, the article is to analyse how the Pohang earthquake can be located and situated.