• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.23-28
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• 2002

This paper describes the machining characteristics of the $MoSi_2$ based composites by electric discharge drilling with various tubular electrodes, besides, Hardness characteristics and microstructures of $Nb/MoSi_2$ laminate composites were evaluated from the variation of fabricating conditions such as preparation temperature, applied pressure and pressure holding time. $MoSi_2$ -based composites has been developed in new materials for jet engine of supersonic-speed airplanes and gas turbine for high- temperature generator. Achieving this objective may require new hard materials with high strength and high temperature-resistance. However, With the exception of grinding, traditional machining methods are not applicable to these new materials. Electric discharge machining (EDM) is a thermal process that utilizes a spark discharge to melt a conductive material, the tool electrode being almost non-unloaded, because there is no direct contact between the tool electrode and the workpiece. By combining a nonconducting ceramics with more conducting ceramic it was possible to raise the electrical conductivity. From experimental results, it was found that the lamination from Nb sheet and $MoSi_2$ powder was an excellent strategy to improve hardness characteristics of monolithic $MoSi_2$. However, interfacial reaction products like (Nb, Mo)$SiO_2$ and $Nb_2Si_3$ formed at the interface of $Nb/MoSi_2$ and increased with fabricating temperature. $MoSi_2$ composites which a hole drilling was not possible by the conventional machining process, enhanced the capacity of ED-drilling by adding $NbSi_2$ relative to that of SiC or $ZrO_2$ reinforcements.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.854-867
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• 2014

In the circumstance that high oil price state is continued over the world, the investment in crude oil development by oil major is a trend of increasing. Recently the number of delivered drill-ship for 5 years has been sharply increased all over the world and about twice than that of past 30 years. As addition to the increase of the drill-ship demand, the operation of drill-ships which is delivered recently is about 3,000 meters, ultra deep sea, on average and the work area is expending. Accordingly the drilling system including the size and length of pipe for drilling has been bigger and bigger and the power supply equipment for operation system also has large capacity. Unlike merchant vessel, high power and high voltage of diesel generators are required for drill-ship for which the demand for V-type 320 bore of diesel generator has increased. It is on the raised that the importance of lubrication oil cleaning for diesel generator on drill-ship which has longer time for construction, and also long term low load operation is unavoidable during commissioning of equipments. Recently it was reported that engine crankpin was damaged due to the hard contact caused by the abnormal wear down(Cam wear) on crankpin and bearing. The same pattern of wear down was found through the inspection on series vessels and the other vessel under commissioning. The purpose of this paper is to analyze of the wear mechanism based on the observation and theories and objective research from actual cases and to prepare the counter measures to avoid foreseeable damage when the lubricating oil is not properly cleaned.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.1
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• pp.71-78
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• 2009

Korea Marine Environment Management Corporation (KOEM) has waste oil facilities in 13 ports to collect and treat waste oil, bilge, etc. from ships based upon the Marine Environment Management Act of Korea and MARPOL 73/78 convention. Those facilities were designed and have been operated simply to discharge water under the level 15 ppm of oil contents. However, bad smells occurred from rotten organic matters in waste water and direct discharge of harmful substances to receiving water caused civil appeals. Therefore, KOEM tried to develop new process for treatment of oily waste water from ships, which could mitigate harmful substances, save cost, calm down civil appeals and contribute to marine environment preservation. This process consists of 3 steps to remove oil contents via gravity variation at first, $O_3$ input to contact water and organism deposition by inputting condensate deposits. Then finally upper water will be discharged, and the deposited substances in the bottom will be compressed through spinning machine to transfer to the designated contractors for treatment of wastes. This is very effective and innovative in that it could reduce 3 or 4 steps compared with existing process and mitigate not only waste oil concentration but also hard resolving materials such as colloid, ABS, phosphorus, nitrogen and bad smells. This method is expected to minimize bad smells and harmful gases, to save more than 10% of maintenance cost, and to arrange the good base for garbage treatment business dealing with waste water and bad smell.

• Journal of Periodontal and Implant Science
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• v.48 no.3
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• pp.182-192
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• 2018

Purpose: The purpose of the present study was to validate an experimental model for assessing tissue integration of titanium and zirconia implants with and without buccal dehiscence defects. Methods: In 3 dogs, 5 implants were randomly placed on both sides of the mandibles: 1) Z1: a zirconia implant (modified surface) within the bony housing, 2) Z2: a zirconia implant (standard surface) within the bony housing, 3) T: a titanium implant within the bony housing, 4) Z1_D: a Z1 implant placed with a buccal bone dehiscence defect (3 mm), and 5) T_D: a titanium implant placed with a buccal bone dehiscence defect (3 mm). The healing times were 2 weeks (one side of the mandible) and 6 weeks (the opposite side). Results: The dimensions of the peri-implant soft tissue varied depending on the implant and the healing time. The level of the mucosal margin was located more apically at 6 weeks than at 2 weeks in all groups, except group T. The presence of a buccal dehiscence defect did not result in a decrease in the overall soft tissue dimensions between 2 and 6 weeks ($4.80{\pm}1.31$ and 4.3 mm in group Z1_D, and $4.47{\pm}1.06$ and $4.5{\pm}1.37mm$ in group T_D, respectively). The bone-to-implant contact (BIC) values were highest in group Z1 at both time points ($34.15%{\pm}21.23%$ at 2 weeks, $84.08%{\pm}1.33%$ at 6 weeks). The buccal dehiscence defects in groups Z1_D and T_D showed no further bone loss at 6 weeks compared to 2 weeks. Conclusions: The modified surface of Z1 demonstrated higher BIC values than the surface of Z2. There were minimal differences in the mucosal margin between 2 and 6 weeks in the presence of a dehiscence defect. The present model can serve as a useful tool for studying peri-implant dehiscence defects at the hard and soft tissue levels.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.12
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• pp.5917-5935
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• 2012

Background: Hepatitis C virus (HCV) causes acute and chronic human hepatitis infection and as such is an important global health problem. The virus was discovered in the USA in 1989 and it is now known that three to four million people are infected every year, WHO estimating that 3 percent of the 7 billion people worldwide being chronically infected. Humans are the natural hosts of HCV and this virus can eventually lead to permanent liver damage and carcinoma. HCV is a member of the Flaviviridae family and Hepacivirus genus. The diameter of the virus is about 50-60 nm and the virion contains a single-stranded positive RNA approximately 10,000 nucleotides in length and consisting of one ORF which is encapsulated by an external lipid envelope and icosahedral capsid. HCV is a heterogeneous virus, classified into 6 genotypes and more than 50 subtypes. Because of the genome variability, nucleotide sequences of genotypes differ by approximately 31-34%, and by 20-23% among subtypes. Quasi-species of mixed virus populations provide a survival advantage for the virus to create multiple variant genomes and a high rate of generation of variants to allow rapid selection of mutants for new environmental conditions. Direct contact with infected blood and blood products, sexual relationships and availability of injectable drugs have had remarkable effects on HCV epidemiology. Hundreds of thousands of people die each year from hepatitis and liver cancer caused by HCV virus infection. Approximately 80% of patients with acute hepatitis C progress into a chronic disease state leading to serious hepatic disorders, 10-20% of which develop chronic liver cirrhosis and hepatocellular carcinoma. The incubation period of HCV is 6-8 weeks and the infection is often asymptomatic so it is very hard to detect at early stages, making early treatment very difficult. Therefore, hepatitis C is called a "silent disease". Neutralizing antibodies are produced against several HCV proteins during infection but the virus mutates to escape from antibodies. Some patients with chronic hepatitis C may have some symptoms such as fatigue, muscle aches, nausea and pain. Autoimmune and immunecomplex-mediated diseases have also been reported with chronic HCV infection.

• Journal of Distribution Science
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• v.15 no.6
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• pp.65-76
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• 2017

Purpose - The quality of customer service has been importantly considered as a way of retaining current customers. Recent development of service industry which based on Information & Communication Technology allows firms to utilize different employees for their businesses. Although it is regarded as important to consider emotional labor of employees working for customers in ICT service industry, little was known the role of emotional dissonance. Thus, current paper focused on emotional labor and tried to identify the factors which influence on employees' intrinsic motivation for married women working in call centers. This study highlighted the influence of the emotional dissonance on the employees' intrinsic motivation, and the moderating influences of work-family conflict on the relationship between emotional dissonance and intrinsic motivation. Research design, data, and methodology - The research samples were gathered from seven call centers of Korean financial institutions located in South Korea. The model of emotional dissonance was developed, which emphasizes the influence of emotional dissonance as a predictor on intrinsic motivation, and then the other model was also introduced to explain how employees' intrinsic motivation were aggravated by work-family conflict. To examine these research models, samples were collected from 468 married women working in call centers of Korean financial institutions located in Seoul. A total of 468 samples were used in the analysis after deleting data of missing value. SPSS 22.0 were utilized for data analysis. Results - The results of current study showed that emotional dissonance is negatively related to intrinsic motivation, and there are significant differences in work-family conflict. Those results generally support the proposed hypotheses. Conclusions - These results suggest that the relationship of intrinsic motivation of married women working in call center for customers' service were influenced by emotional dissonance, which outcomes were interacted not by face-to-face contact with their customers, but by emotional contacts. Managerially, these findings suggest the one who emphasize the quality of customer's service of call center need to introduce the programs for minimizing both of emotional dissonance and work-family conflict. These findings also suggest that the service quality via intrinsic motivation of married women working in call center is hard to be accomplished without considering the factors of emotional dissonance and work-family conflict.

• Journal of the Korean institute of surface engineering
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• v.49 no.6
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• pp.580-586
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• 2016

Cr-Si-Al-N coating with different Si content were deposited by hybrid physical vapor deposition (PVD) method consisting of unbalanced magnetron (UBM) sputtering and arc ion plating (AIP). The deposition temperature was $300^{\circ}C$, and the gas ratio of $Ar/N_2$ were 9:1. The CrSi alloy and aluminum targets used for arc ion plating and sputtering process, respectively. Si content of the CrSi alloy targets were varied with 1 at%, 5 at%, and 10 at%. The phase analysis, composition and microstructural analysis performed using x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) including energy dispersive spectroscopy (EDS), respectively. All of the coatings grown with textured CrN phase (200) plane. The thickness of the Cr-Si-Al-N films were measured about $2{\mu}m$. The friction coefficient and removal rate of films were measured by a ball-on-disk test under 20N load. The friction coefficient of all samples were 0.6 ~ 0.8. Among all of the samples, the removal rate of CrSiAlN (10 at% Si) film shows the lowest values, $4.827{\times}10^{-12}mm^3/Nm$. As increasing of Si contents of the CrSiAlN coatings, the hardness and elastic modulus of CrSiAlN coatings were increased. The morphology and composition of wear track of the films was examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy, respectively. The surface energy of the films were obtained by measuring of contact angle of water drop. Among all of the samples, the CrSiAlN (10 at% Si) films shows the highest value of the surface energy, 41 N/m.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.597-607
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• 2023

Purpose: The Ministry of Employment and Labor has been working hard to ensure the safety of workers due to heavy rain during natural disasters as the responsible ministry in charge of preventing industrial accidents and health problems for workers. Accordingly, the Ministry of Employment and Labor intends to analyze actual cases of responding to heavy rain disasters and suggest ways to improve the response system. Method: An emergency response system implemented to respond to heavy rain disasters with an internal expert group composed of those in charge of disaster work at headquarters, local government offices, and Korea Occupational Safety and Health Agency, and an external expert group composed of professors, consulting representatives, and disaster managers from other ministries. Contents on self-inspection by industry, workplace inspection, use of serious siren, safety management and restoration work guidance were reviewed. Result: First of all, it is necessary to check the regular contact system from time to time, and it is also necessary to prepare and distribute detailed self-checklists for each industry. In addition, it is necessary to check the implementation of self-inspection when inspecting workplaces, and it seems necessary to have measures to increase the readability of information notified through serious disaster sirens. In addition, since safety work is done in the form of a contract, it seems necessary to prepare specific safety guidelines. Conclusion: In order to protect the lives of workers due to seasonal harm and risk factors, unlike the passive coping methods of the past, abnormal weather should not be regarded as an unexpected situation, and it should be actively and preemptively responding beyond the conventional framework.

• The Journal of Korean Academy of Prosthodontics
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• v.61 no.3
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• pp.234-244
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• 2023

Tooth wear refers to the loss of dental hard tissue caused by various physiological and pathological causes, and excessive pathological wear can cause complications such as pathological changes in dimensions, occlusal disharmony, loss of function, and aesthetic problems. The cause of tooth wear can be caused by attrition, abrasion, corrosion and abfraction, and it is known to act in a multifactorial etiology in interocclusal activity. In patients with excessive pathological wear, it is important to determine whether or not the vertical dimension of occlusion is reduced, and complete oral rehabilitation should be achieved with the adaptation of the neuromuscular and temporomandibular joint through accurate diagnosis and analysis. The patient in this case was a 63-year-old male patient, who presented discomfort to cold beverage due to severe tooth wear. After analysis of the patient's vertical dimension of occlusion, a full mouth rehabilitation was performed with increasing vertical dimension of occlusion. The goal of treatment was to improve the occlusal plane with the equal-intensity contact of all teeth, harmonious anterior guidance and immediate disclusion of all posterior contacts. After rehabilitation, the patient was satisfied with function and esthetic appearance.

• Journal of Venture Innovation
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• v.5 no.4
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• pp.157-178
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• 2022

The economy has deteriorated worldwide due to COVID-19, and the domestic economy has also been hit hard. Accordingly, the government implemented unprecedented financial support policies related to COVID-19 to solve the financial difficulties experienced by SMEs. In addition, as the spread of COVID-19 continued, the government implemented guidelines and measures along with recommendations for non-face-to-face contact. Organizations in the public and private sectors have introduced non-face-to-face work methods. Considering this situation, this study investigated the impact of COVID-19-related financial support policies on technological innovation of SMEs. External support is important for corporate innovation, but internal capabilities are also important. Therefore, the effect of entrepreneurship on product innovation was identified. In addition, as the non-face-to-face work method was activated, the effect of smart work was identified by comparing companies that introduced smart work and companies that did not. As a result of the analysis, entrepreneurship showed a positive (+) effect regardless of the introduction of smart work. Financial support policies related to COVID-19 were found to show mixed results according to the type of support.