• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.3
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• pp.159-165
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• 2021

This study introduces a topology optimization method for the simultaneous design of macro-scale structural configuration and unit structure variation to ensure effective heat conduction. Shape changes in the unit structure depending on its location within the macro-scale structure result in micro- as well as macro-scale design and enable better performance than using isotropic unit structures. They result in functionally graded composite structures combining both configurations. The representative volume element (RVE) method is applied to obtain various thermal conductivity properties of the multi-material based unit structure according to its shape change. Based on the RVE analysis results, the material properties of the unit structure having a certain shape can be derived using machine learning. Macro-scale topology optimization is performed using the traditional solid isotropic material with penalization method, while the unit structures composing the macro-structure can have various shapes to improve the heat conduction performance according to the simultaneous optimization process. Numerical examples of the thermal compliance minimization issue are provided to verify the effectiveness of the proposed method.

• Korean Journal of Environmental Biology
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• v.39 no.2
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• pp.169-183
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• 2021

This study was carried out to investigate the flora of the Hanbando wetland (Yeongwol-gun, Gangwon-do) from April 2019 to May 2020. Vascular plants were grouped into 508 taxa, comprising 93 families, 309 genera, 456 species, 10 subspecies, 37 varieties, and 5 forms. Among the investigated 508 taxa, 2 endangered species, 8 rare plants, and 8 endemic plants were identified. The specific plants by floristic region were grouped into 71 taxa including, 3 taxa of grade V, 10 taxa of grade IV, 15 taxa of grade III, 17 taxa of grade II, and 26 taxa of grade I. Naturalized and ecosystem disturbing plants were grouped into 57 taxa and 5 taxa, respectively. The percentage of naturalized plants species and urbanization index were estimated to be 11.2% and 17.8%, respectively. This study provides important basic information for the efficient management of Hanbando wetland, which possess a high conservation value since it is forms part of the list of Ramsar wetlands.

• Journal of the Korean Institute of Gas
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• v.25 no.1
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• pp.20-29
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• 2021

During multi-stage fracturing in a low permeable shale formation, stress interference occurs between the stages which is called the "stress shadow effect(SSE)". The effect may alter the fracture propagation direction and induce ununiform geometry. In this study, the stress shadow effect on the hydraulic fracture geometry and the well productivity were investigated by the commercial full-3D fracture model, GOHFER. In a homogeneous reservoir model, a multi-stage fracturing process was performed with or without the SSE. In addition, the fracturing was performed on two shale reservoirs with different geomechanical properties(Young's modulus and Poisson's ratio) to analyze the stress shadow effect. In the simulation results, the stress change caused by the fracture created in the previous stage switched the maximum/minimum horizontal stress and the lower productivity L-direction fracture was more dominating over the T-direction fracture. Since the Marcellus shale is more brittle than more dominating over the T-direction fracture. Since the Marcellus shale is more brittle than the relatively ductile Eagle Ford shale, the fracture width in the former was developed thicker, resulting in the larger fracture volume. And the Marcellus shale's Young's modulus is low, the stress effect is less significant than the Eagle Ford shale in the stage 2. The stress shadow effect strongly depends on not only the spacing between fractures but also the geomechanical properties. Therefore, the stress shadow effect needs to be taken into account for more accurate analysis of the fracture geometry and for more reliable prediction of the well productivity.

• Journal of Convergence for Information Technology
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• v.10 no.12
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• pp.1-8
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• 2020

The purpose of this study was to identify the factors that influence the organizational commitment of clinical dental hygienists to contribute to manpower management. The subject of the study was 195, and the following results were obtained as a result of collecting and analyzing data using a self-filling questionnaire from March 10 to April 20, 2020. The degree of organizational commitment, job satisfaction, and internal marketing according to general characteristics were analyzed by t-test and one-way ANOVA, and post-test was set to'Scheffe'. The correlation between organizational commitment, job satisfaction, and internal marketing showed a significant positive correlation with job satisfaction (r=0.689) and internal marketing (r=0.678). The factors influencing organizational commitment were multiple regression analysis, and the influencing factors for organizational commitment were internal marketing and job satisfaction. The most influential factor was job satisfaction, and the explanatory power was 56.1%.As a result, the internal marketing of clinical dental hygienists was found to be related to job satisfaction and organizational commitment, and the factor that most affected was job satisfaction. Therefore, institutional and administrative support from dental medical institutions is needed to improve job satisfaction, which has an impact on organizational commitment of clinical dental hygienists.

• Journal of the Korean Applied Science and Technology
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• v.38 no.1
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• pp.19-28
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• 2021

Corrosion is the degradation of metals by reaction with the environment. It is difficult to completely remove. Corrosion proceeds rapidly after the protective barrier is destroyed, and several reactions occur that alter the composition and properties of the metal surface and local environments, such as diffusion of metal cations into the matrix, the formation of oxides, and local pH changes. The study of corrosion of steel and iron is of theoretical and practical interest and is receiving considerable attention. Acid solutions, which are widely used in industrial pickling, acid descaling, cleaning and acidification of oil wells, require the use of corrosion inhibitors to suppress corrosion attacks on metallic materials. Physical removal of rust requires expensive special equipment, and chemical removal of it can cause corrosion or shorten the life of the metal. In this study, an eco-friendly rust cleaner was developed using cosmetics and food materials by applying the concept of perm reducing agent and chelate, and applied to remove rust from industrial and hot water pipes and various industrial devices. As a result, it was found that rust cleaners remove rust more effectively and safely compared to conventional treatment methods. At the same time, the rust removal efficiency was 1.75 to 2.5 times better for industrial piping and 1.56 to 2.2 times better for boiler hot water than conventional methods.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.515-520
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• 2022

In context awareness using multiple sensors, when using sensor data detected and sent by each sensor, it is necessary to give different weights for each sensor. Even if the same type of sensor is configured for the same situation, sometimes it is necessary to assign different weights due to other secondary factors. It is inevitable to assign weights to events in the real world, and it can be said that a weighting method that can be used in a context awareness system using multiple sensors is necessary. In this study, we propose a weighting method for each sensor that reports to the host while the sensors continue to detect over time. In most IoT environments, the sensor continues the detection activity, and when the detected value shows a change pattern beyond a predetermined range, it is basically reported to the host. This can be called a kind of data stream environment. A weighting method was proposed for sensing data from multiple sensors in a data stream environment, and the new weighting method was to select and assign weights to data that indicates a context change in the stream.

• Journal of the Korea Convergence Society
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• v.12 no.11
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• pp.169-184
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• 2021

Recent advances in science and technology leveraged various artistic tools. Interactive art based on various media technologies became popular in a short period, and is widely appreciated as a new form of art. This new form of art has a different method of expression from traditional art such as painting or sculpture. It aims to strike a balance among the artist, audience, and piece of art through interaction between the work and viewers. Viewers can take part in the creation process, going beyond the conventional way of art appreciation. This paper analyzes interactive art production techniques based on human senses from the artist's perspective. "Simulation-experience model" will be suggested after looking at several example artworks. Charming, which was produced based on this model, will be introduced and its meaning will be analyzed. The objective of this paper is to predict the future of interactive art and changes in the art form by studying interactive art production techniques based on human senses. We believe that the prediction is helpful in understanding the artistic and technological value and the social influence of interactive art in the future.

• Korean Journal of Veterinary Service
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• v.44 no.4
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• pp.271-281
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• 2021

Pathogenic Escherichia coli (E. coli) is one among the most important agents of diarrhea in calves. From January to December 2021, 108 isolates from feces of calves with diarrhea were investigated for enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), shiga toxin-producing E. coli (STEC), enteroaggregative E. coli (EAEC), and enteroinvasive E. coli (EIEC) using real-time PCR. In addition, the genes for F5, F17 and F41 fimbriae were detected by PCR. The most frequently isolated pathotypes were EPEC/STEC (29 isolates), and ETEC/EPEC/STEC (29 isolates). ETEC/EPEC, and ETEC/STEC were also found in 10 isolates. EPEC, STEC, and ETEC were detected in 13, 11, and 6 respectively. EAEC, and EIEC was not detected. Antimicrobial resistance test was carried out by agar disc diffusion method with 14 antimicrobials. Among 108 pathogenic E. coli isolates, 107 isolates were resistant to at least one of 14 antibiotics used in this study, 99 (91.7%) were resistant to two or more antimicrobials, and a single remarkable isolate was resistant to 14 antimicrobials. The isolates were primarily resistant to penicillins, streptomycin, tetracycline, ceftiofur, Trimethoprim/sulfamethoxazole, Kanamycin, and Ciprofloxacin. The high rate of resistance in pathogenic E. coli, sometimes to multiple drugs, may complicate future options for treating human infections. These results may bu used for diagnosis and therpeitic purposes in calves with diarrhea.

• Journal of Korean Medical classics
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• v.35 no.1
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• pp.103-116
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• 2022

Objectives : To look at the medical law reformation of Korean Medicine hospitals through the establishment and management of the Jaehan Oriental Medicine Hospital, which was the first Korean Medicine Hospital in South Korea. Methods : Revisions of the medical law since the establishment of the National Medical Act in 1951 up until 1973 when the 'Korean Medicine hospital' first entered the medical institution category were examined. Based on the revised contents, the establishment and management of the Jaehan hospital were examined. Results & Conclusions : The first mentioning of 'Korean Medicine hospital' in the medical law took place on Feb 16, 1973 when the medical law was completely revised. After law regulations on Korean Medicine hospitals were established, the fist Korean Medicine hospital was founded on Nov. 24th, 1973 according to act 2533 of the medical law. This is the Jaehan Oriental Medicine Hospital, which is the predecessor of what we now know as the Daegu Korean Medicine University Hospital. Although the Jaehan hospital was registered as a legitimate Korean Medicine hospital in November of 1973, it had already started medical practice in December of 1970. While it was established according to the standards of medical law, it changed its institution category from 'Korean Medicine hospital' to 'affiliated Korean Medicine clinic' based on another clause within the same law. The decade from 1960 to 1970 was a time when national economy was developing, and the field of medicine and medical institutions were also booming. As such, revisions in the medical law seems to not have been able to keep up with what was happening in reality. To meet the patients' right to move or to manage diseases which Korean Medicine was taking responsibility for, a medical institution with inpatient capacity was required. Therefore it is possible that the Jaehan hospital which had already been providing such a role could have been a sample case for reference in the medical law revision process.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.601-609
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• 2022

Jack-up drilling rigs are mobile offshore platforms widely used in the offshore oil and gas exploration industry. These are independent, three-legged, self-elevating units with a cantilevered drilling facility for drilling and production. A typical jack-up rig includes a triangular hull, a tower derrick, a cantilever, a jackcase, living quarters and legs which comprise three-chord, open-truss, X-braced structure with a spudcan. Generally, jack-up rigs can only operate in water depths ranging from 130m to 170m. Recently, there has been an increasing demand for jack-up rigs for operating at deeper water levels and harsher environmental conditions such as waves, currents and wind loads. All static and dynamic loads are supported through legs in the jack-up mode. The most important issue by society is to secure the safety of the leg structure against collision that causes large instantaneous impact energy. In this study, nonlinear FE -analysis and verification of the requirement against collision for 35MJ recommended by DNV was performed using LS-Dyna software. The colliding ship used a 7,500ton of shore supply vessel, and five scenarios of collisions were selected. From the results, all conditions do not satisfy the class requirement of 35MJ. The loading conditions associated with chord collision are reasonable collision energy of 15M and brace collisions are 6MJ. Therefore, it can be confirmed that the identical collision criteria by DNV need to be modified based on collision scenarios and colliding members.