• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.27-34
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• 2016

In the train system, railway vehicles are connected in a line. Therefore, this feature should be considered in composing network topology in a train system. Besides, inter-car communication should be distinguished from in-car communication. As for the inter-car communication, the hybrid topology was proposed to use rather than the conventional ring, star, daisy-chain, and bus topologies. In the hybrid topology, a number of cars are bound to be a group. Then star topology is used for the communication in a group and daisy-chain topology is used for the communication between groups. Hybrid topology takes the virtue of both star and daisy-chain topologies. Hence it maintains communication speed with reducing the number of connecting cables between cars. Therefore, it is important to choose the number of cars in a group to obtain higher performance. In this paper, we focus on the optimization of hybrid topology for railway cars. We first assume that the size of data and the frequency of data production for each car is identical. We also assume that the importance for the maximum number of cables to connect cars is variable as well as the importance of the communication speed. Separated weights are granted to both importance and we derive the optimum number of cars in a group for various number of cars and weights.

• Water for future
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• v.15 no.2
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• pp.11-22
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• 1982

This study is to find out the reasonable drainage system of sewerage in connection with the geographical conditions, the form of city, and the problem of sewerage in and around Seoul. (1) In supplying the sewerage sewer, the separating system is desirable in connection with the problem of sewerage disposal in future. However, in the existing urban district, the conjunction system is used because of the large amount invested according to the diversion of the sewer of the separation system and the influence of the traffic communication. The sewer of the separating system should be used in the case of the fundamental reconstruction of structure as the redevelopment of the urban district or the subway and new-development of area. Therefore, the separating system should be used completely until the goal year. (2) Drainage area was divided for the natural flowing, considering that the 38 streams and topography paly a role of the main stream of drainage. There are the branches, Guyui, Dug-island, Jayang, Hannam, Banpo, Amsa whose divisions are impossible. In these branches, the drain planning was suggested a forced control method by using the exiting pond age and the pumping station. (3) The best available method which improbes the water quality in Han river is as follows. The sewerage is catched and carried to the sewerage disposal plant by establishing the intercept sewer in both or one side of stream. At the same time, the groudwater volume which springs in each stream is drained separatively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1707-1721
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• 2014

Half-depth panels were developed with the merits of CIP (Cast In Place) decks and precast decks for constructability and fast construction. In this paper, details of half-depth panels with pre-tensioning were suggested. For evaluation of structural performance, five half-depth panel specimens were fabricated and static tests were conducted. The cross-sections of these specimens were composed of pre-tensioned half-depth panels and pre-tensioned two-span half-depth panels. Test parameters were the amount of the prestressing force and the longitudinal reinforcements. Static tests on simply-supported slabs showed that ultimate strength was 1.55 times greater than calculated nominal strength. The flexural strength was only 10 % increased and the influence on crack width control was negligible when the member of tendons was increased twice. For two-span continuous specimens, the ultimate strength increased 1.2 times and 1.38 times respectively as the reinforcement was additionally provided. The verified half-depth panels by this research can be effectively utilized for the fast replacement or construction of bridges.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.557-565
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• 2021

Path-following control is considered as one of the most fundamental skills to realize autonomous navigation of marine vessels in the ocean. This study addresses with the path-following control for a ship in which there are environmental disturbances in the directions of the surge, sway, and yaw motions. The guiding principle and back-stepping method was utilized to solve the ship's tracking problem on the reference path generated by a virtual ship. For path-following control, error dynamics is one of the most important skills, and it extends to the research fields of automatic collision avoidance and automatic berthing control. The algorithms for the guiding principles and error variables have been verified by numerical simulation. As a result, most error variables converged to zero values with the controller except for the yaw angle error. One of the most interesting results is that the tracking errors of path-following control between two ships are smaller than the existing safe passing distances considering interaction forces from near passing ships. Moreover, a trade-off between tracking performance and the ship's safety should be considered for determining the proper control parameters to prevent the destructive failure of actuators such as propellers, fins, and rudders during the path-following of marine vessels.

• The Journal of the Acoustical Society of Korea
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• v.40 no.5
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• pp.408-416
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• 2021

In the ultrasonic dispersion, in order to avoid direct contact of the radiation surface of ultrasonic transducers with a liquid sample, the liquid sample is separated by a glass container and it receives ultrasonic energy through an acoustic medium. The transmission efficiency of the ultrasonic energy in the multi-layered ultrasonic system is an important factor. In this study, we suggested a method that can improve the ultrasonic energy transfer efficiency by using a propylene glycol solution as a liquid matching layer in the multi-layered acoustic system. In this method, a propylene glycol solution was filled between the Langevin-type ultrasonic transducer and the luminol solution and the sonoluminescence phenomena in the luminol solution, which is caused by nonlinear effect of high power ultrasound radiated from the transducer, was examined by using a Photo Multiplier Tube (PMT). The transmission efficiency depending on the concentration of propylene glycol solution was observed, and we can see that as the concentration of the propylene glycol solution increased, the matching effect increased while the acoustic attenuation increased. It was confirmed that there is an optimal concentration compromised these two conflicting conditions, and the optimum concentration of the propylene glycol solution was determined experimentally.

• Environmental and Resource Economics Review
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• v.28 no.2
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• pp.201-229
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• 2019

This paper estimates the effects of generation mix changes in the $7^{th}$ and $8^{th}$ Basic Plan for Long-term Power Supply and Demand from two aspects: economic efficiency through electricity prices and environmental performance through $CO_2$ and air pollutants(NOx, SOx, PM) emissions. Particularly, we examined additional generation mix conversion paths that take into account the trade-off between economic efficiency and environmental performance through scenario analysis. According to our results, the conversion from the $7^{th}$ plan to the $8^{th}$ plan should increase the electricity prices in the mid- and long-term, while reducing GHG and air pollutants emissions at the same time. The alternative generation mix that combines $7^{th}$ and $8^{th}$ plans shows that there exists a path to mitigate the trade-off between economic and environmental in the long-term. It will be next to impossible to derive a optimal generation mix that simultaneously considers the core values, such as supply stability, environmental performance, economic efficiency, energy safety and energy security, when establishing the power supply and demand plan. However, by exploring the effects of various generation mix paths and suggesting near-optimal paths, people can best choose their direction after weighhing all the paths when deciding on a forward-looking generation mix in the long term.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.6
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• pp.86-97
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• 2011

This study analyzed the necessity of the tentatively-named "Framework Act on Landscape Architecture" as an umbrella law in the field of landscape architecture regarding legal, industrial, and academic aspects and is intended to provide basic data to suggest the optimal legal system and legislative proceedings to control it. This study can be summarized as follows: First, a form of framework act on landscape architecture is appropriate for a compromise between ideal type and political framework. Some content is suitable for proclamatory character including present and future issue related to the landscape architecture fields. Second, legislative proceedings are more reasonable as motions coming from assembly proposals rather than government. Motions by assembly proposal recommend the following procedure: submission of a legislative bill by an assemblyperson, passing of a permanent commission, review by government, leading approval by emphasis on correspondence with the principle to carry out government affairs, proclamation. Third, a frame based on content and form can be made up of a total of 7 chapters 34 articles. The function must include the following: the suggestion of direction for government policy, the systematization of the institution and what it includes, the control of government administration, a public service system regarding public relations for landscape architecture and so on. The results of this study will form a social consensus about the necessity of a framework act regarding landscape architecture fields and contribute to informing the importance of landscape architecture as related to other industrial fields.

• Journal of Ethics
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• no.88
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• pp.103-122
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• 2013

This paper aims to study on conceptual suitability or unfitness of Silhak(實學). It is general that by criticizing Chujahak(朱子學) or beyond the limitation of Seonglihak(性理學), Silhak has developed practical tendency to reforming the society in the middle and end of Chosen Dynasty, related to the context of Korean national reflection in modern times. However, it is unfortunate to be understood. As presented in Chosenwangjosillok(『朝鮮王朝實錄』), there has been a few usages in the term 'Silhak'. In short, it was different from its contemporary meaning. At that time, it was usually used to have the meaning of Gyunghak(經學), compared to Sajanghak(詞章學), or rarely, of 'the true study' or 'the practical study'. Therefore, it is to claim that its conception has been manipulated or exaggerated very seriously. Since 1930s, in particular, its conception has been misused in interpreting works of Jung Yak-Yong by some scholars, such as Jung In-Bo, Moon Il-Pyung and An Jae-Hong, who tried to apply the term to overcome the Japanese colonial era symbolised as modernity based on the future life of Korea. Even though their attempt has led to have crucial discussions on the conceptions of Silhak, it has an unnecessary result that there has been a new and totally different understanding of Silhak in South Korea, North Korea, China, Japan, etc., which means that the unsustainable conception of Silhak has been one of major problems in studying of Silhak. To give an practical solution, I would try to make sense of 'time spirit' whose scholars studied Silhak in the middle and end of Chosen Dynasty. A problem, however, is that a scholar group in the name of Bukhakpa(北學派) had certain links and bonds. This is because many scholars studying of Silhak were usually features out of the main stream, which made them it difficult to form any various groups. That is to say, it seems to be natural that they have dreamed of utopian imaginations less than of overlapping points in reality. To sum up, it would be concluded at least that any approach to human lives and thoughts in the given conceptions of Silhak, e.g. ethical thoughts of Silhak, enables us to be indifferentiated to take its true meaning and time spirit of Chosen Dynasty. To be disenchanted of its social roles in Chosen Dynasty, fundamentally, it should be escaped from the wrong net of illusions and sings in understanding Silhak in certain eclectic steps.

• The Journal of Korean Philosophical History
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• no.41
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• pp.155-184
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• 2014

This Paper is research for Yulgok School(栗谷學派)'s lixue(禮學) in the first half of 17c centering around Uiremunhae(疑禮問解) and Uiremunhaesuk(疑禮問解續). Uiremunhae and Uiremunhaesuk are a book between Kim Jangsaeng(金長生) Kim Jip(金集) and his follower's questions & answers about li. A book or letter of questions & answers about li is useful for comprehension of lixue's opinion, especially questions & answers about controversial li shows their critical mind and a foundation of cognition for li. Thus I make showing then situation of Kim Jangsaeng and his follower in relates to understanding and performing Zhuxi's family rituals on analyzing questions & answers about controversial li. Kim Jangsaeng Kim Jip and his follower's characteristic of lixue are several on analyzing Uiremunhae. First, Kim Jangsaeng and his follower researched for Zhuxi's family rituals with systematic approach and in-depth research, and detailed in reference to the Classic of li, Zhuxi, Zheongyi(程?), Zangzai(張載)'s thoery of li and chinese lixue data, and Lee Hwang(李滉), Lee Yi(李珥), Song Yikpil(宋翼弼), Jeong Goo(鄭逑)'s thoery of li and korean lixue data. Next, on questions & answers about controversial li, Kim and his follower basically maintained following Zhuxi's family rituals. Zonfa, sacrificial rituals and funeral rituals are all such that, and if there happened omission and contradiction in Zhuxi's family rituals, they refered to Zhuxi's theory of li on the collected works of Zhuxi and the analects of Zhuxi and searched righteous li by historial invesigation. Then, Kim and his follower critically were in succession to Lee Yi and Song Yikpil's thoery of li. finally, They also had to considered then situation on li(Zhuxi's family rituals' li and ancient li)'s operation and actualizatin on considering principle and mind of li.

• Journal of the Korean Geographical Society
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• v.28 no.4
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• pp.379-391
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• 1993

Present-day world economy is characterized by : technology nationalism, economic regionalism, market protectionism, multinational corporations, efc. All nations are striving for intensifying national economic rivalry and seeking after their own interests above everything else. Many regions of the world are also forming trading blocs, which could negatively affect nonmember states. The ultimate way to meet these difficulties is to establish production facilities in the countries imposing trade regulations. However, as the existing models of direct forrign investment (DFI) do not account for the particular nature of Korean firm's DFI activities, a new point of departure is imperative. It is because of this that Korean firms have only limited firm-specific advantages, the basic precondition of extant DFI theories, compared with their developed counterparts.