• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.791-799
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• 2020

Launched in October 2019, Northrop Grumman's MEV-1 was the world's first unmanned mission demonstrating the practical feasibility of on-orbit servicing. Although the concept of on-orbit servicing was proposed several decades ago, it has been developed to various mission concepts providing services such as orbit change, station keeping, propellant and equipment supply, upgrade, repair, on-orbit assembly and production, and space debris removal. The historical success of MEV-1 is expected to expand the market of on-orbit servicing for government agencies and commercial sectors worldwide. The on-orbit servicing essentially requires the utilization of a highly propellant efficient electric propulsion system due to the nature of the mission. In this study, the space mission analysis for a simple on-orbit mission involving Hall thruster is conducted, which is life extension mission for geostationary orbit satellites. In order to analyze the mission, design space exploration for various Hall thruster design variable combinations is performed. The values of design variables and operational parameters of Hall thruster suitable for the mission are proposed through design space analysis and optimization, and mission performance is derived. In addition, the direction of further improvement for the current on-orbit mission analysis process and space mission analysis involving Hall thruster is reviewed.

• Journal of Elementary Mathematics Education in Korea
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• v.18 no.1
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• pp.1-17
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• 2014

Instructions for the commutative property of multiplication at elementary schools tend to be based on checking the equality between the quantities of 'a times b 'and b' times a, ' for example, $3{\times}4=12$ and $4{\times}3=12$. This article critically examined the approaches to teach the commutative property of multiplication from Kant's perspective of mathematical knowledge. According to Kant, mathematical knowledge is a priori. Yet, the numeric exploration by checking the equality between the amounts of 'a groups of b' and 'b groups of a' does not reflect the nature of apriority of mathematical knowledge. I suggest we teach the commutative property of multiplication in a way that it helps reveal the operational schema that is necessarily and generally involved in the transformation from the structure of 'a times b' to the structure of 'b times a.' Distributive reasoning is the mental operation that enables children to perform the structural transformation for the commutative property of multiplication by distributing a unit of one quantity across the other quantity. For example, 3 times 4 is transformed into 4 times 3 by distributing each unit of the quantity 3, which results in $3{\times}4=(1+1+1){\times}4=(1{\times}4)+(1{\times}4)+(1{\times}4)+(1{\times}4)=4+4+4=4{\times}3$. It is argued that the distributive reasoning is also critical in learning the subsequent mathematics concepts, such as (a whole number)${\times}10$ or 100 and fraction concept and fraction multiplication.

• Environmental and Resource Economics Review
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• v.19 no.3
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• pp.659-688
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• 2010

Climate change induced by global warming has recently begun to inspire developed nations to introduce a new paradigm, called the sustainable (Green) growth, which entails both the prevention of environmental pollution and the attainment of sustainable growth. The sustainable (Green) growth is founded upon environmental factors that drive a new force of economic progress without deteriorating nature. Thus, the conservation of the environment under the new growth paradigm can be compatible with economic growth, although this was not feasible under conventional economic relations, called the Environmental Kutzets Curve. Sustainable (Green) finance is essential to achieving Green growth efficiently and effectively. Since the financial system for Green growth is at the early stage of implementation, the application of strategies for sustainable (Green) finance should be preceded by proper initiation and protection from the government. In order to establish a feasible strategy for financing green growth, we suggest an effective financial supporting system, taking different operational forms upon the broader stage of technological progress in each individual company.

• Journal of Educational Research in Mathematics
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• v.14 no.4
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• pp.367-385
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• 2004

This study intends to compare the way of introducing fractions in elementary mathematics textbooks of south and those of north Korea. After thorough investigations of the seven differences were identified. First, the mathematics textbooks of south Korea use concrete materials like apples when they introduce equal partition context, while those of north Korea do not use that kind of concrete materials. Second, in the textbooks of south Korea, equal partition of discrete quantities are considered after continuous ones are introduced. This is different from the approach of the north Korean text-books in which both quantities are regarded at the same time. Third, the quantitative fraction which refers to the rational number with unit of measure at the end of it, is hardly used in the textbooks of south. However, the textbooks of north Korea use it as the main representations of fractions. Fourth, in the textbooks of south Korea, vanous activities related to fractions are more emphasized, while in the textbooks of north Korea, various meanings of fractions textbooks from south and north Korea focused on the ways of introducing partition approach and equivalence relation as operational schemes of fractions, the following play an important role before defining fraction. Fifth, the textbooks of south Korea introduce equivalent fractions with number one using number bar, and do not consider the reason why that sort of fractions are regarded. On the contrary, the textbooks of north Korea introduce structural equivalence relation by using various contexts including length measure and volume measure situations. Sixth, whereas real-life contexts are provided for introducing equivalent fractions in the textbooks of south Korea, visual explanations and mathematical representations play an important role in the textbooks of north Korea. Seventh, the means of finding equivalent fractions are provided directly in the textbooks of south Korea, whereas the nature of equivalent fractions and the methods of making equivalent fractions are considered in the textbooks of north Korea.

• Journal of Korea Port Economic Association
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• v.34 no.3
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• pp.113-132
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• 2018

Mokpo port marked the $131^{st}$ anniversary of its opening in 2018. while the Mokpo has taken the new port development initiatives, it is limited by inefficient port functioning due to the lack of maritime port policy and government investment. Hence, port logistics has not been activated. Additionally, studies on Mokpo port have not been conducted, and knowledge available on the port is declarative in nature. On the other hand, research on port competitiveness focuses on how to analyze the factors that determine port competitiveness. Therefore, this study was intended to expand the existing research on Mokpo port and conduct an analysis of non-competitiveness factors and suggested improvements by considering the operational aspect of Mokpo port. In this regard the importance of non-competitiveness factors was assessed through an analytic hierarchy process(AHP) analysis and the influence of the non-competitiveness factors was analyzed through an fuzzy structural modeling(FSM) analysis. The result of the AHP analysis show ed the important non-competitiveness factors included the deactivation of industrial complexes around Mokpo port, the number of liner route, the cost of the pilot and tug. Accor ding to the FSM analysis, the top level included the non-competitive factors at Mokpo port; the intermediate level included the number of liner routes, cost of pilot and tug, enrance and clearance fee, costs of inland transportation, fee for port facilities, and loading and unloading costs; and the bottom level comprised the most non-competitive factors including the deactivation of industrial complexes around Mokpo port, hinterland connectivity, access to international port, incentives, and cost of transportation and storage. Based on the results of analysis, improvements were suggested for non-competitive factors of Mokpo.

• Korean Journal of Heritage: History & Science
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• v.51 no.4
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• pp.208-223
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• 2018

This paper focuses on strategies and issues involving a joint inscription of an Intangible Cultural Heritage element to UNESCO through multinational cooperation and conclusive characteristics and the significance of the multinational filing. The case of "Falconry", which was jointly filed by 18 State Parties including ROK and inscribed on the Representative List of the Intangible Cultural Heritage of Humanity of UNESCO on 2010, was analyzed as the main object of discussion The issues can be summarized as follows: First; State Parties that participated at the joint nomination process got to grasp the purpose of the multinational nomination mechanism a lot better than before through drawing up the nomination forms. Especially, we learned that the inscription of the falconry eventually has to contribute to the perception of ICH in general and applying that knowledge at the submission of the multinational file was the major aspect for the inscription on the list in 2010 and the extension of the inscription 2012. Second; the very nature of prosecution of the multinational nomination, State Parties are given opportunities to communicate and cooperate over their shared ICH element, through which a mutual understanding of other cultures and the national characteristics of other countries - which means implementing the very ideology of UNESCO- to contribute to cooperation and peace among nations through multinational nominations. Third, the falconry, according to the Operational Directives of the <>, has a chance to be deemed a Best Practice case, since it continuously extends through more and more State Parties participating to the multinational file. Extension of a Representative List of the Intangible Cultural Heritage of Humanity element can help defusing the tension caused by identifying the owner of the intangible heritage and can mean more awareness of the purpose of the convention.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.3
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• pp.137-149
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• 2021

Cable-stayed bridges are infrastructure facilities of a highly public nature; therefore, it is essential to ensure operational safety and prompt response in the event of a collapse or damage caused by natural and social disasters. Among social disasters, impact accidents can occur in bridges when a vehicle collides with a pier or when crashes occur due to aircraft defects. In the case of offshore bridges, ship collisions will occur at the bottom of the pylon. In this research, a procedure to evaluate the structural behavior of a cable-stayed bridge for aircraft impact is suggested based on a numerical analysis approach, and the feasibility of the procedure is demonstrated by performing an example assessment. The suggested procedure includes 1) setting up suitable aircraft impact hazard scenarios, 2) structural modeling considering the complex behavior mechanisms of cable-stayed bridges, and 3) structural behavior evaluation of cable-stayed bridges using numerical impact simulation. It was observed that the scenario set in this study did not significantly affect the target bridge. However, if impact analysis is performed through various scenarios in the future, the load position and critical load level to cause serious damage to the bridge could be identified. The scenario-based assessment process employed in this study is expected to facilitate the evaluation of bridge structures under aircraft impact in both existing bridges and future designs.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.21-27
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• 2023

As a means of helping ships navigate safely, navigational aids in operation in the maritime envirionment require periodic management, and due to the nature of the environment, it is difficult to visually check the exact state. As a result, the smart navigation aid system, which improves route safety and operational efficiency, utillizes expertise including sensors, communications, and information technology, unlike general route markings. The communication environment of the smart navigation aid system, which aims to ensure the safety of the navigators operating the ship and the safety of the ship, uses a wireless communication network in accordance with the marine environment. The ship collects the information necessary for the maritime environment on the land and operates. In this process, there is a need to consider the wireless communication security guideline. Basically, based on IHO S-100 a standard for facilitating data exchange and SECOM, which provides an interface for safe communication. This paper research a security system for safe communication in a maritime environment. The security system for the basic interface based on the document was presented, and there were some vulnerabillties to data exchange due to the wireless communication characteristics of the maritime environment, and the user authetication part was added considering the vulnerability that unauthorized users can access the service.

• Journal of Christian Education in Korea
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• v.63
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• pp.121-150
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• 2020

The important developmental tasks of young adults are based on encounter and identity. These problems of encounter and identity are also connected to the instinct of longing for the "face" of primary caregivers, who acknowledge and affirm themselves as their cherished children. James Loder emphasizes that human "face pursuit instinct" later reaches "formal-operational stage" and leads to religious yearning for God as "the Eternal Face." This pursuit of "face" and "the Eternal Face" is an existential and ontological move to find out "Who am I?" through meaningful encounters. Religious psychologist Carl Jung also points out that scientific thinking has contributed to the liberation of humans from superstitious beliefs. But this has also led to the loss of the precious value of human spirit and the sense of unity with nature. Jung emphasizes that "symbolic play" should help learners and counseler face-to-face with their unconscious mind. By doing so, learners can overcome the wounds and scars of unconsciousness and mature toward the true self. James Loder is a scholar who critically introduced Jung's "unconscientious confrontation" therapy to his educational theory. Beyond Jung's unconsciousness and "symbolic play," Loder proposed transformational education for the learners to participate in meaningful changes through interaction between human spirit and the Holy Spirit. With many young adults wandering around in their existential voids, it is clear that functional and socializational education cannot overcome their problems and developmental crisis. This developmental crisis requires a foundation of identity and intimacy in the encounter with God, the "Eternal Face." Therefore, this study suggests that when Jung's "unconscious confrontation" and Loder's "transformation logic" are employed, transformational Christian education for the healthy self-identity and intimacy of young adults can be accomplished. This inquiry presents not only theoretical reflection, but also the reactions of young adults and actual feedback obtained through implementing transformational Christian education for young adults. Through all of these endeavors, this inquiry was completed by proving that "Transformational Christian Education for Young Adults" is an educational theory that can yield actual results and abound fruits. (This enquiry was undertaken by the support of the research fund of PUTS 2020.)

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.3
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• pp.202-210
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• 2013

As incomes increase, interest in ocean leisure picks up. As a result, a lot of research and developments on hull form design and production of planing boats, mostly used for ocean leisure, are needed. Analysis in researches on resistance of planing boats shows that resistance characteristic of planing boats is different from resistance characteristic of general boats because the former is fast, and its wetted surface is very small. Using Savitsky formula widely used in the calculation of effective horse power in shipbuildingyards, and propulsion system and engine manufacturers, this study calculated total resistance of a research planing boat. Then it analyzed the flow characteristics of the planing boat through theoretical analysis and wind tunnel experiment, and computed air resistance and lift force by changes of speed and trim angle. It also compared and analyzed result of theoretical analysis and experiment of the ratio of air resistance to total resistance under variations of velocity and trim angle. When the study is used to estimate more accurate effective horse power, it is expected to remedy abuses of unnecessarily installing high-powered engine. As nature disasters due to abnormal changes of weather increase, interest in greenhouse gas grows. International Maritime Organization (IMO) legislated Energy Efficiency Design Index (EEDI) and Energy Efficiency Operational Indicator (EEOI) to reduce ship greenhouse gas emissions. But this index will be applied to over 400 tons ships, small ships, emitting more greenhouse gases than larege ships per unit power, will dodge the regulations. Thus, this study indicated a problem by calculating greenhouse gas emissions of an ocean leisure planning boat (a small ship), and suggested the need for EEDI of small ships.