• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.15-23
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• 2021

In this paper, service life for RC(Reinforced Concrete) substructure subjective to carbonation was evaluated through deterministic and probabilistic method considering field investigation data and Design Code(KDS 14 20 40). Furthermore changes in service life with increasing COV(Coefficient of Variation) and equivalent safety index meeting the same service life were studied. From the investigation, the mean and its COV of cover depth were evaluated to 70.0 ~ 90.0 mm and 0.2, respectively. With intended failure probability of 10.0 % and 70 mm of cover depth, service life decreased to 137 years, 123 years, and 91 years with increasing COV of 0.05, 0.1, and 0.2, respectively. In the case of 80 mm of cover depth, it changes to 179 years, 161 years, and 120 years with increasing COV. The equivalent safety index meeting the same service life from deterministic method showed 1.66 ~ 3.43 for 70 mm of cover depth and 1.61 ~ 3.24 for 80 mm of cover depth, respectively. The various design parameters covering local environment and quality condition in deterministic method yields a considerable difference of service life, so that determination of design parameters are required for exposure conditions and parameter variation.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.1
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• pp.73-83
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• 2019

As the awareness of the importance of Start-up increases, the number of entrepreneurs who decide to start their career is gradually increasing. However, the rate of start-up failure is still high and the qualitative level is very low due to lack of start-up performance. In this study, we analyzed the effect of entrepreneurship capability and start-up support system on start-up performance. To that end, 361 valid data were collected from businesses that were established less than seven years ago in Jeollabuk-do on August 1, 2018 and used for study verification through SPSS 21 and AMOS 21. First, the entrepreneurial competence (entrepreneurial competence, managerial competency) has a positive effect on the start-up support system and the technical competency has no significant effect. Second, entrepreneurial competence (entrepreneurial competence, managerial competency, technical competency) has a significant effect on entrepreneurial performance. However, entrepreneurial competence has a meaningful effect on the start-up performance of entrepreneurs with a negative (-) effect. Third, it was found that the start - up support system had a positive effect on the start - up performance. Finally, the start - up support system proved to have mediating effect between entrepreneurial competence and start - up performance. The implications of this study are as follows. In order to increase the start-up performance of the start-up companies, it is proved that increasing the capacity of the start-ups is an important factor. In addition, empirical studies have proved that the use of start-up support system is an important factor that directly or indirectly has a significant effect on start-up performance, We have made meaningful implications that actively supporting and utilizing entrepreneurship is necessary to enhance start-up performance.

• Journal of Navigation and Port Research
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• v.42 no.6
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• pp.478-485
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• 2018

Aids to Navigation (AtoN) is one of the marine traffic safety facilities that promotes the safety of maritime traffic and enhance ship's operational efficiency. However, functional failure of AtoN due to ship's collision or bad weather conditions leads to inconvenience or navigational risk to various users such as the ship operators. For insstance, the largest container port in Korea, Busan Port has experienced a total of 400 AtoN accidents in the past 12 years (2006-2017).Therefore, an average of 20.6 days of recovery time is required, which increases the maritime safety anxiety for AtoN users. is the objective of this study was to present the quantitative support of the users for the prevention of AtoN accidents and the improvement of the feasibility of implementing more efficient management in Korea. A survey was conducted on the users of Busan port areas to investigate general perception of AtoN in general and the accidents that have happened, and to estimate the economic value of navigational risk reduction by implementing effective AtoN management measure. Using the representative non-market valuation method for environmental or public goods known as contingent valuation method (CVM), the economic value granted to users for the AtoN services in Busan port was estimated to at least 16 billion won. Therefore, these finding could be used by AtoN managers and/or policy makers as a valuable data to identify the users' need of various AtoN services including Busan Port and to establish and implement more efficient management plan.

• Journal of Korea Technology Innovation Society
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• v.22 no.3
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• pp.382-415
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• 2019

This study analyzes the impact of exclusive subcontracting on the input, behavior, and output of innovation in manufacturing industries of Korea. Based on the analysis of pooled cross-sectional data of 6,029 small venture firms, this study proved that the exclusive subcontracting between small venture firms and large enterprises are lowering R&D investment of small venture firms. Second, the innovation activities of small venture firms including the ratio of R&D personnel and the scope of cooperation and partnership with external organizations were lower than those of small venture firms that have non-exclusive or no relations with large enterprises. Third, the innovation performance of small venture firms such as the number of patent applications, the ratio of sales by new products, and the cumulative sales growth rate was lower than those of small venture firms that have non-exclusive or no relations with large enterprises. This study verifies that the exclusive subcontracting relationships significantly weaken the innovation process and performance of small venture firms systematically, resulting in a kind of market failure in which small venture firms have almost no incentive to facilitate innovation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.7
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• pp.801-809
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• 2017

The purpose of this study is to contribute to the prevention of ship collisions by investigating real ship collision cases and statistically analyzing causes of human error for captains and Officers of the Watch (OOW). This study encompassed a total of 109 cases for 218 vessels, which were suitable for the analysis of ship accidents between merchant ships or merchant ships and fishing boats over the 7 years from 2010 to 2016. Data was collected while classifying vessels according to type, Give-way and Stand-on vessels, along with the cause of human error. Factors causing human error were identified after focusing on the cause of each collision given by the OOW ; frequency and cross tabulation analyses were conducted using SPSS, a statistical analysis tool. As a result, the main causes of human error by an OOW in a ship collision situation were that lookout was neglected in a Give-way vessel including radar surveillance (74.3 %) or continuous observation of an opponent vessel was carried out (17.4 %). A major factor for Stand-on vessels was failure to act to avoid collision with another vessel (63.3 %). In particular, most neglect for lookout type merchant ships occurred after the opponent ship was first observed, and a common cause of lookout neglect and neglect of duty was a focus on other tasks during navigational watch time.

• Korean Journal of Heritage: History & Science
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• v.46 no.4
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• pp.78-89
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• 2013

For safe conservation treatment of damaged accessory relics that were unearthed, the quality of the material should be accurately identified through a nondestructive analysis and failure analysis. This study provides the basic conservational scientific data regarding material analyses and conservation treatment that were conducted for 11 relics, including amber and agate that were discovered during the repair of Geumsansa Temple's Hall of Maitreya Buddha and Left Attendant Buddhas in June 2008. An ultraviolet analysis, SEM-EDS analysis and FT-IR microscope analysis revealed that the physical and chemical characteristics of the 11 relics are the same as those of amber. It is inferred that the cracks and exfoliation of the surface of most amber relics is attributable to darkening of the color due to C=C bond oxidation. It is also assumed that cracks and exfoliation occurred from the weathered layer on the amber surface. As such, it is appropriate to engage in conservation treatment of the damaged amber relics by using $Paraloid^{(R)}$ B67 reinforcing agent that is diluted in nonpolar solvent. The greatest care is needed for future handling of organic artifacts.

• Tuberculosis and Respiratory Diseases
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• v.82 no.1
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• pp.81-85
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• 2019

Background: Bronchoscopy is a useful diagnostic and therapeutic tool. However, the clinical use of high-flow nasal cannula (HFNC) in adults with acute respiratory failure for diagnostic and invasive procedures has not been well evaluated. We present our experiences of well-tolerated diagnostic bronchoscopy as well as cases of improved saturation in hypoxaemic patients after a therapeutic bronchoscopic procedure. Methods: We retrospectively reviewed data of hypoxaemic patients who had undergone bronchoscopy for diagnostic or therapeutic purposes from October 2015 to February 2017. Results: Ten patients (44-75 years of age) were enrolled. The clinical purposes of bronchoscopy were for diagnosis in seven patients and for intervention in three patients. For the diagnoses, we performed bronchoalveolar lavage in six patients. One patient underwent endobronchial ultrasonography with transbronchial needle aspiration of a lymph node to investigate tumour involvement. Patients who underwent bronchoscopy for therapeutic interventions had endobronchial mass or blood clot removal with cryotherapy for bleeding control. The mean saturation ($SpO_2$) of pre-bronchoscopy in room air was 84.1%. The lowest and highest mean saturation with HFNC during the procedure was 95% and 99.4, respectively. The mean saturation in room air post-bronchoscopy was 87.4%, which was 3.3% higher than the mean room air $SpO_2$ pre-bronchoscopy. Seven patients with diagnostic bronchoscopy had no hypoxic event. Three patients with interventional bronchoscopy showed improvement in saturation after the procedure. Bronchoscopy was well tolerated in all 10 cases. Conclusion: This study suggests that the use of HFNC in hypoxaemic patients during diagnostic and therapeutic bronchoscopy procedures has clinical effectiveness.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.8
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• pp.215-222
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• 2021

In order to alleviate the limited resource problem and interference problem in cellular networks, the dual connectivity technology has been introduced with the cooperation of small cell base stations. In this paper, we design a new efficient and fair resource allocation scheme for the dual connectivity technology. Based on two different bargaining solutions - Generalizing Tempered Aspiration bargaining solution and Gupta and Livne bargaining solution, we develop a two-stage radio resource allocation method. At the first stage, radio resource is divided into two groups, such as real-time and non-real-time data services, by using the Generalizing Tempered Aspiration bargaining solution. At the second stage, the minimum request processing speeds for users in both groups are guaranteed by using the Gupta and Livne bargaining solution. These two-step approach can allocate the 5G radio resource sequentially while maximizing the network system performance. Finally, the performance evaluation confirms that the proposed scheme can get a better performance than other existing protocols in terms of overall system throughput, fairness, and communication failure rate according to an increase in service requests.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.594-602
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• 2021

This study aims to identify the learning behavior patterns recognized by students to find effective tutoring operational methods, and further analyze the impact of learning behavior patterns on academic performance and learning satisfaction. To this end, 105 participants in the tutoring program at D University based in Busan Metropolitan City collected data and conducted descriptive statistics, correlation analysis and regression analysis according to research problems. First, the study found that students who participated in tutoring had the most environment-dependent and self-taught learning behavioral styles and environment-independent and self-taught learning behavioral style. Second, the correlation between learning behavioral styles and academic achievement and learning satisfaction shows that there is a high correlation between positive and cooperative learning behavioral styles and environment-independent and self-taught learning behavioral styles. Third, regression analysis on academic achievement and learning satisfaction showed that positive and cooperative learning behavioral styles significantly affects learning satisfaction, but environment-independent and self-taught learning behavioral style, environment-dependent and self-taught learning behavioral style, and passive learning behavioral style were not significant. These results suggest that from the school perspective, learning behavior can be recognized as an important factor in students' academic success and failure, so instructors need to check learners' learning behavior patterns and provide appropriate tutoring teaching and learning design plans.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.6
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• pp.111-119
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• 2019

The purpose of this study is to investigate the shear strength of reinforced concrete beam according to beam section size and shear reinforcement ratio. A total of nine specimens were tested and designed concrete compressive strength is 24 MPa. The main variables are shear reinforcement ratio and beam section size fixed with shear span to depth ratio (a/d = 2.5), the tensile reinforcement ratio (${\rho}=0.013$) and width to depth ratio (h/b = 1.5). The test specimens were divided into three series of S1 ($225{\times}338mm$), S2 ($270{\times}405mm$) and S3 ($315{\times}473mm$), respectively. The experimental results show that all specimens represent diagonal tensile failure. For $S^*-1$ specimens (d/s=0), the shear strength decreased by 33% and 46% with increasing the beam effective depth, 26% and 33% for $S^*-2$ specimens (d/s=1.5) and 16% and 20% for $S^*-3$ specimens (d/s=2.0) respectively. As the shear reinforcement ratio increases, the decrease range in shear strength decreases. In other words, this means that as the shear reinforcement ratio increases, the size effect of concrete decreases. In the S1 series, the shear strength increased by 39% and 41% as the shear reinforcement ratio increased, 54% and 76% in the S2 series and 66% and 100% in the S3 series, respectively. As the effective depth of beam increases, the increase range of shear strength increases. This means that the effect of shear reinforcement increases as the beam effective depth increases. As a result of comparing experimental values with theoretical values by standard equation and proposed equation, the ratio by Zsutty and Bazant's equation is 1.30 ~ 1.36 and the ratio by KBC1 and KBC2 is 1.55~.163, respectively. Therefore, Zsutty and Bazant's proposed equation is more likely to reflect the experimental data. The current standard for shear reinforcement ratio (i.e., $S_{max}=d/2$) is expected to be somewhat relaxed because the ratio of experimental values to theoretical values was found to be 1.01 ~ 1.44 for most specimens.