• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.17-25
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• 2022

The pintle injector has many advantages in the key characteristics of a liquid rocket engine, such as combustion stability, combustion efficiency, and wide range of comprehensive thrust control, design and manufacture, and test fired under supercritical conditions. The pintle injector is manufactured with a rectangular, single-row orifice for thrust control and production considerations. In order to verify the combustion performance of the pintle injector and its potential as a commercial injector, the combustion characteristics were analyzed by varying the TMR (Total Momentum Ratio) and BF (Blockage Factor). The result of the hot firing test showed that the heat flux increased as TMR increased, and it confirmed that the characteristic velocity efficiency was more affected by BF than TMR. Suppose a single-row pintle injector with efficiency characteristics insensitive to changes in TMR can achieve high efficiency at low fuel differential pressure conditions. In that case, the variable pintle injector's design flexibility can be increase.

• Asia Marketing Journal
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• v.8 no.1
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• pp.105-132
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• 2006

The major purpose of this study is to investigate the impact of environmental uncertainties and logistics resources capabilities mediated by relational norms and logistics services on logistics performance in the industrial products. The 272 data were collected from the key informants who were working at the logistics-related departments in the H Heavy Industries & Construction and HSD Engine. The following results were verified using structural equation modeling. First, environmental uncertainties such as dynamism and heterogeneity unexpectedly had insignificant effects on relational norms such as information exchange and flexibility and logistics services such as product availability and on-time delivery. Second, logistics resource capabilities showed unique effects based upon its component's characteristics. For example, Logistics Information Systems did not have direct impact on logistics services but had indirect effect on logistics services via relational norms. On the other hand, logistics resources such as logistics specific assets and transportation service competencies had direct impact on logistics services but not on relational norms. Third, relational norms between transaction partners significantly affected logistics services but had insignificant effects on logistics performance such as logistics costs reduction and delivery qualities. Fourth, consistent with several studies, excellent logistics services between industrial purchaser and suppliers based upon relational norms did have significant effect on logistics performance such as delivery consistency and delivery qualities. Finally, the empirical results in this study could be strategic logistics management guidelines based upon the theoretical relationships among the environmental uncertainties, logistics information systems, logistics resources, relational norms, logistics services, and logistics performance.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.5
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• pp.79-92
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• 2019

When asked about the success factors of successful entrepreneurs and celebrities, he says he was lucky. The remarkable fact is that the attitude about luck is different. However, despite the fact that the belief that we believe is lucky is actually a dominant concept, there has not been much scientific verification of luck. In this study, we saw good luck not being determined randomly by the external environment, but by being able to control luck through the internal attributes of individuals. This study is significant that we have empirically elucidated what kind of efforts have gained good luck, whereas previous research has largely ended in vague logic where luck ends up with an internal locus of control among internal entrepreneurial qualities and efforts can make a successful entrepreneur. We introduced the concept of good luck belief to avoid confirmation bias, which is, to interpret my experience in a direction that matches what I want to believe, and used a good luck belief questionnaire in previous studies and tried to verify that those who have a good belief can increase entrepreneurial opportunity capability through planned happenstance skills. The reason for choosing the entrepreneurial opportunity capacity as a dependent variable was based on the conventional research, that is, the process of recognizing and exploiting the entrepreneurial opportunity is an important part of the entrepreneurship research For empirical research, we conducted a questionnaire survey of a total of 332 people, and the results of the analysis turned out that the belief of good luck has all the positive impacts of planned happenstance skills' sub-factors: curiosity, patience, flexibility, optimism and risk tolerance. Second, we have shown that only the perseverance, optimism, and risk tolerance of planned happenstance skills' sub-factors have a positive impact on this opportunity capability. Thirdly, it was possible to judge that the sub-factors of planned happenstance skills, patience, optimism, and risk tolerance, had a meditating effect between belief in luck and entrepreneurial opportunity capability. This study is highly significant in logically elucidating that people in charge of business incubation and education can get the specific direction when planning a training program for successful entrepreneur to further enhance the entrepreneurial opportunity ability, which is an important ability for the entrepreneur's success.

• Journal of Navigation and Port Research
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• v.38 no.4
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• pp.367-371
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• 2014

When the crew or passengers fall into the water due to marine accident of vessel, it is very important to rescue them quickly. In the case of marine accidents, most people in distress have been wearing a lifejacket, so if the GPS and Cospas-Sarsat communication module will be integrated within the lifejacket, it is easy to rescue them. In this paper, development of the dual band lifejacket-integrated antenna for GPS and Cospas-Sarsat communication is discussed. The antenna with the FR-4 substrate of 0.2mm thickness for flexibility was designed that it can be fitted close to the shoulder of the life jacket and operate at 1.575GHz and 406MHz. The GPS communication antenna was implemented with a ring-slot antenna having a circular polarized characteristic and a meander type linear polarized antenna is used as Cospas-Sarsat communication. The two antennas are fed by a single microstrip line and an open stub is used to minimize the mutual interference between the two antennas. The performance of the fabricated antenna attached to the life vest is confirmed by the measurement of the return loss at GPS and Cospas-Sarsat frequency bands.

• Membrane Journal
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• v.27 no.6
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• pp.499-505
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• 2017

The increasing number of natural disasters resulting from anthropogenic greenhouse gas emissions has prompted the development of a gas separation membrane. Carbon dioxide ($CO_2$) is the main cause of global warming. Organic polymeric membranes with inherent flexibility are good candidates for use in gas separation membranes and poly(dimethyl siloxane)(PDMS) specifically is a promising material due to its inherently high $CO_2$ diffusivity. In addition, poly(vinyl pyrrolidine)(PVP) is a polymer with high $CO_2$ solubility that could be incorporated into a gas separation membrane. In this study, poly(dimethyl siloxane)-poly(vinyl pyrrolidine)(PDMS-PVP) comb copolymers with different compositions were synthesized under mild conditions via a simple one step free radical polymerization. The copolymerization of PDMS and PVP was characterized by FTIR. The morphology and thermal behavior of the produced polymers were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Composite membranes composed of PDMS-PVP on a microporous polysulfone substrate layer were prepared and their $CO_2$ separation properties were subsequently studied. The $CO_2$ permeance and $CO_2/N_2$ selectivity through the PDMS-PVP composite membrane reached 140.6 GPU and 12.0, respectively.

• Journal of the Korean Society for Library and Information Science
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• v.57 no.2
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• pp.379-408
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• 2023

This case study reports on the redevelopment of a course, Local Culture Information Theory offered by the Department of Library and Information Science at C University, into a capstone design course using a project-based learning approach. In collaboration with a local community youth organization, the redesigned course provided an opportunity for LIS students to develop and implement a digital literacy program that enabled high school students to use a variety of digital multimedia technologies to complete a project of digital Human Library featuring video, audio, and digital are such as webtoons. Through semi-structured interviews with 5 students and 3 staff from partner organizations, this study reports on course development process, the establishment of local partnerships, project outcome, as well as suggestions for improvements. In addition, a qualitative analysis of the participating students' interview responses using the Framework for 21st Century Learning (P21) found they developed and improved 11 skills across three core areas: life and career skills including self-direction, project management, collaboration with diverse teams, flexibility, responsibility, leadership; learning and innovation skills including communication and collaboration, problem-solving, creativity, and critical thinking; and information, media, and technology skills through media creation. Lessons learned and recommendations from this case study may be useful for other LIS programs and faculty interested in implementing project-based learning or developing capstone design courses.

• Journal of The Korean Association For Science Education
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• v.34 no.2
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• pp.93-105
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• 2014

Group creativity has recently been heightened as a core competence in the 21st century. Therefore, there is a need for introduction of concepts on design thinking emphasizing the collaboration and empathy to science education as an effective method for fostering group creativity. Understanding design thinking for effective introduction should be preceded, so we explore the characterizations of design thinking through the generic model overlay method, focus group interview, and critical incident technique analysis. The results reveal 4 cluster units of competency and 15 core competencies. The collaboration cluster consists of 5 competencies and they are as follows: organization of the team, communication, self-control, persuasiveness, and initiative competency. The integrative thinking cluster consists of 3 competencies and they are as follows: analytical, strategic, and intuitive thinking competency. The human-centeredness cluster consists of 3 competencies and they are as follows: user-orientation, relationship building, and interpersonal understanding competency. The multidisciplinary cluster consists of 4 competencies and they are as follows: achievement orientation, information seeking, curiosity, and flexibility competency. Findings are expected to provide the basic data for developing programs and establishing strategies in order to foster group creativity as well as introducing design thinking to science education effectively.

• Journal of the Korean GEO-environmental Society
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• v.19 no.2
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• pp.37-44
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• 2018

Ballasted track has been widely used due to its flexibility. However, the plastic deformation of ballasted track causes the evolution of track geometrical errors, and hence it requires continuous maintenance; increase in number of trains, weight, and speed expedites maintenance frequency and cost as well. Ballast stiffness is well-known as an indicator of design and maintenance. In this regard, this paper aims to suggest the method to measure ballast track stiffness using light-weight deflectometer (LWD) and thus verify its applicability as a maintenance measure. Preliminary field tests determined simple field testing protocol to measure track stiffness. The apparent ballast stiffness by LWD shows good corelation with TQI (Track Quality Index) and maintenance length. That is, as average of apparent stiffness increase, TQI and tamping length decrease exponentially. Therefore, apparent stiffness can be used as an index for ballast condition assessment.

• Journal of the Korean Geographical Society
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• v.40 no.1 s.106
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• pp.27-46
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• 2005

Land suitability assessment(LSA) is a useful method to assess land characteristics according to its physical, locational, and environmental characteristics, and then to classify it into several categories based on its usability and the necessity for conservation. Therefore, the credibility of this assessment result depends on the rationality of assessment method such as computation of suitability values and the criteria of ranking the land grade. This study focused on identifying problems in current LSA method by critically reviewing it, and aimed to suggest a suitable method for the assessment of land suitability. As a alternative method in this study, linear transformation method was used for scoring factors instead of critical values and the weight for each assessment factor. and all values of those factors were added to produce comprehensive suitability values. Those values were ordered and categorizied with suitability level based on the ratio of square measure. After comparing existing LSA method to the suggested alternative method, it is concluded that the alternative method was more suitable to assess the characteristics of lands than existing LSA method. This method was also suitable to represent the characteristics of various assessment factors. Field survey using satellite image clearly revealed the suitability of the alternative method compared to an existing method of land assessment. Furthermore, the alternative method of grading the land suitability improves the problem of using standardiZiation method and gives more flexibility, which makes this method very rational.

• Journal of Adhesion and Interface
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• v.21 no.3
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• pp.107-112
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• 2020

Recently, the atomically thin transition-metal dichalcogenide (TMD) semiconductors have attracted much attention owing to their remarkable properties such as tunable bandgap with high carrier mobility, flexibility, transparency, etc. However, because these TMD materials have a significant drawback that they are easily degraded in an ambient environment, various attempts have been made to improve chemical stability. In this research article, I report a method to improve the air stability of WSe₂ one of the TMD materials via surface passivation with an h-BN insulator, and its application to field-effect transistors (FETs). With a modified hot pick-up transfer technique, a vertical heterostructure of h-BN/WSe₂ was successfully made, and then the structure was used to fabricate the top-gate bottom-contact FETs. The fabricated WSe₂-based FET exhibited not only excellent air stability, but also high hole mobility of 150 ㎠/Vs at room temperature, on/off current ratios up to 3×10⁶, and 192 mV/decade of subthreshold swing.