• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.1015-1026
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• 2002

As per increasing research interest in the field of collaborative computing in recent year, the importance of security issues on that area is also incrementally growing. Generally, the persistency of collaborative system is facilitated with conventional authentication and cryptography schemes. It is however, hard to meet the access control requirements of distributed collaborative computing environments by means of merely apply the existing access control mechanisms. The distributed collaborative system must consider the network openness, and various type of subjects and objects while, the existing access control schemes consider only some of the access control elements such as identity, rule, and role. However, this may cause the state of security level alteration phenomenon. In order to handle proper access control in collaborative system, various types of access control elements such as identity, role, group, degree of security, degree of integrity, and permission should be taken into account. Futhermore, if we simply define all the necessary access control elements to implement access control algorithm, then collaborative system consequently should consider too many available objects which in consequence, may lead drastic degradation of system performance. In order to improve the state problems, we propose a novel access control framework that is suitable for the distributed collaborative computing environments. The proposed scheme defines several different types of object elements for the accessed objects and subjects, and use them to implement access control which allows us to guarantee more solid access control. Futhermore, the objects are distinguished by three categories based on the characteristics of the object elements, and the proposed algorithm is implemented by the classified objects which lead to improve the systems' performance. Also, the proposed method can support scalability compared to the conventional one. Our simulation study shows that the performance results are almost similar to the two cases; one for the collaborative system has the proposed access control scheme, and the other for it has not.

• Journal of Bio-Environment Control
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• v.21 no.4
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• pp.459-465
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• 2012

This study analyzed the effect of semi-rigid rafter-purlin cross-linking connection and driven steel pipe base on the static behavior of plastic greenhouse (PG). To promote the time and cost efficiency of the assembly process, each cross-linking connections of space arch type grid that consists of rafter and purlin is linked with steel-wire buckles, and each end of the rafters was driven directly to the ground to support the PG structure. However, in the design process, cross-linking connections and bases are idealized by being categorized as fully rigid or frictionless pinned, which does not appropriately reflect actual conditions. This study takes a full-scale loading test of PG and analyzes the effect of member cross-linking connections and driven steel pipe base on the behavior of a structure. The analysis provided a basis for determining the rigidity factor of member cross-linking nodes needed for finite element analysis, and the reliability of the result regarding the static behavior of PG.

• Plant Biotechnology Reports
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• v.3 no.3
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• pp.175-182
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• 2009

Simple, reproducible, high frequency, improved plant regeneration protocol in Eastern Cottonwood (Populus deltoides) clones, WIMCO199 and L34, has been reported. Initially, aseptic cultures established from axillary buds of nodal segments from mature plus trees on MS liquid medium supplemented with $0.25mg\;1^{-1}$ KIN and $0.25mg\;1^{-1}$ IAA. Nodal and internodal segments were found to be extra-prolific over shoot apices during course of aseptic culture establishment, while $0.25mg\;1^{-1}$ KIN concentration played a stimulatory role in high frequency plant regeneration. Diverse explants, such as various leaf segments, internodes, and roots from in vitro raised cultures, were employed. Direct plant regeneration was at high frequency of 92% in internodes, 88% in leaf segments, and 43% in root segments. This led to the formation of multiple shoot clusters on established culture media with rapid proliferation rates. Many-fold enhanced shoot elongation and growth of the clusters could be achieved on liquid MS medium supplemented with borosilicate glass beads, which offer physical support for proliferating shoots leading to faster growth in comparison to semi-solid agar or direct liquid medium. SEM examination of initial cultures confirmed direct plant regeneration events without intervening calli. In vitro regenerated plants induced roots on half-strength MS medium with $0.15mg\;1^{-1}$ IAA. Rooted 5- to 6-week-old in vitro regenerated plants were transferred into a transgenic greenhouse in pots containing 1:1 mixture of vermicompost and soil at $27{\pm}2^{\circ}C$ for hardening and acclimatization. 14- to 15-week-old well-established hardened plants were transplanted to the field and grown to maturity. The mature in vitro raised poplar trees exhibited a high survival rate of 85%; 4-year-old healthy trees attained an average height of 8 m and an average trunk diameter of 25 cm and have performed well under field conditions. The regeneration protocol presented here will be very useful for undertaking genetic manipulation, providing a value addition to Eastern Cottonwood propagation in future.

• Journal of Korea Port Economic Association
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• v.35 no.2
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• pp.109-126
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• 2019

The Panmunjom Declaration adopted by the leaders of South and North Korea on April 27, 2018, has created an environment conducive for peace and cooperation in the Korean Peninsula. In the June of last year, South Korea has joined the Organization for Cooperation between Railways (OSJD). The membership of OSJD has established a solid foundation for restoring a multimodal logistics system that connects the Korean peninsula to Eurasia countries, including China and Russia. In this paper, a questionnaire survey targeting working-level experts was conducted to find the barriers in constructing multimodal logistics that efficiently connect the port-continental railways of the Korean peninsula and the Eurasian nations. Survey items were divided into five categories-border crossing procedures, technology, facilities, operation, and government support. As a result, among the most important problems of international multimodal logistics in Eurasia that need to be solved on priority include improving transshipment facilities, eliminating inspection carried out at every country for transit, simplifying documents for customs clearance, and minimizing the changes in freight rates. In conclusion, for vitalizing the connection between the Korean peninsula and the continental railways, it is necessary to develop a transshipment system to facilitate the changes in tracks at the borders by making a joint effort with the international community. Second, railway and operational systems in South Korea, North Korea, China, and Russia should be standardized. Third, international cooperation among South Korea, North Korea, China, and Russia is essential for simplifying customs clearance at borders, priority departure of domestic cargo, sharing information about the changes in freight rates, and so on. Finally, the government should come up with measures to secure the quantity of cargo required to form block trains, while developing new business models.

• Cross-Cultural Studies
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• v.49
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• pp.201-228
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• 2017

In Korean society, universities represent institutions of higher education. Industrialization and economic development led to a small number of elite groups at the helm of these institutions. However, our society has encouraged a lifelong system of learning, and apparently, the present university system does not represent an ideal scenario. The Korean government recognized the need for appropriate changes. The events associated with the implementation of related policies occurred at the Ewha Womans University (Seoul) last year. This article is based on the notion of lifelong education to further our understanding of the role of university in the absence of a consensus among university and college members regarding lifelong learning in our society. As an alternative, we looked at the case of France, which is adopting a lifelong education system and implementing related policies ahead of us. Despite regulatory challenges and adaptation of the role of public education in lifelong learning, France has laid a solid foundation. In our case, we are recognizing the need to prepare for lifelong learning. In particular, it is necessary to increase public awareness of education by clearly recognizing our national responsibility and increasing the financial support to universities, accordingly. Above all, the role and attitude of universities must change, along with the perception of its members.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.3
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• pp.12-21
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• 2011

We investigated the location and surveillance system of fortress using inter-visibility analysis between fortress and the capital of the Silla Dynasty. The digital terrain model(DTM) was generated with $10{\times}10m$ grid in Arcview 3.2. Then three fortresses lines(Myeonghwal-sanseong, Namsan-shinseong, Seohyeong-sanseong) were superimposed on the DTM. 4 results of this study were drew out from the cumulative visibility analysis. First, the most of fortress lines which showed the high visible frequency from the Sila-Capital(538 viewpoints) have a good aspect toward the capital. It means that 3 fortresses secured the visibility to the capital. Second, the cumulative visibility analysis from 3 fortresses generated evenly distributed visible frequency across the inside of fortress. It shows that the inner area of fortress is more advantageous to command during the war. On the contrary, a number of invisible(vulnerable) regions which is scattered on the outside were supplemented by adjacent fortress. Third, the north area of the Sila-captial showed the highest visible frequency generated by sum up the visibility from 3 fortresses. The northern captial is placed within 4km distance easy to support at the Myeonghwal and Seohyeong-sanseong. We proved that the Sila-capital had organized a solid surveillance system by 3 fortresses. Fourth, we could infer the practical process of fortress layout from comparing a cumulative visibility map. For the secure of visibility and defense systems, the fortress line would form a rising shape to the peak. This practical location theory can replace the vague common location theory that the fortress would constructed on two thirds of mountain height. It will be an empirical method in the ancient remains research.

• Phonetics and Speech Sciences
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• v.13 no.2
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• pp.19-25
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• 2021

It has been widely recognized that there are two varieties of lateral liquid /l/, which are light /l/ (a non-velarized allophone) and dark /l/ (a velarized allophone). However, this categorical view has been challenged in recent studies, both on articulatory and acoustic aspects. The purpose of this study is to investigate whether to consider /l/ velarization as a continuum in American English and provide supporting data. A spontaneous American English speech database called the Buckeye Speech Corpus was used for the material. The formant frequencies of /l/ in each syllable position were measured and analyzed statistically. The formant frequencies of /l/ in each syllable position, especially F2 values, were significantly different from each other. The results showed that there were other significantly different varieties of /l/ in American English, which support the continuum view on /l/ velarization. Regarding the effect of the adjacent vowel, the backness of the adjacent vowels was shown to affect the degree of /l/ velarization, regardless of the syllable position of the lateral liquid. This result will help provide a solid ground for the continuum view.

• Journal of Wetlands Research
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• v.23 no.1
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• pp.85-93
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• 2021

Sewage separation which often involves installing a new pipe to separate wastewater flow from stormwater runoff flow can be costly and depends highly on its feasibility in a site. To be able to develop a potentially more economical alternative that can also lessen major road traffic disturbance during this process, a different approach where a smaller sewage separator pipe is installed inside an existing combined sewer pipe was investigated. A small-scale of a box sewer and the proposed sewage separator pipe was constructed in the laboratory to observe and compare the deposition of solids and other solid-associated major pollutants at different flow rates. In addition, three-dimensional flow simulations considering five different scenarios were conducted using Ansys Fluent to observe the effect of the proposed sewage separator pipe to the hydraulic flow if installed inside the combined sewer pipe. Results revealed that the deposition of TSS, TCOD, TN, and TP were reduced by at least 60% when the wastewater was conveyed by the sewage separator pipe instead of the combined sewer pipe. Moreover, the flow simulations conducted showed that there was little to no major disturbance in hydraulic flow and velocity distribution when the sewage separator was installed inside a straight pipe and even at pipe transitions such as intersections, turns, and drop in elevation. Considering the pipe dimensions and the results of the study, the proposed approach can be promising in terms of reduction in pollutant deposition without a major effect on the hydraulic flow. Further investigation and cost-analysis should be done in the future to support these preliminary findings and help alleviate the problems caused by combined sewer overflows by introducing an alternative approach.

• Journal of Christian Education in Korea
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• v.68
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• pp.279-306
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• 2021

This paper intends to say that children's worship as a liturgy for children living in modern society is an important place to support children's personal development and experience of coziness necessary for their personal development. To this end, this thesis first regards modern society as an unstable society, analyzes fluid society and individualism as the causes, and deals with changes in educational style accordingly. In a fluid society, children are not provided with a solid form and lasting environment that supports personality development, and the education style changed under the influence of individualism and pluralism requires a heavy task of determining the direction of one's life and constantly making choices and decisions. Therefore, children need rules and forms that help them live together, and they need a space that can give them comfort that helps them develop their personality. As an argument for this, second, this paper deals with the concept and function of the liturgy in order to understand the worship of children as the liturgy. The third deals with the elements necessary for the development of children's personality that can be experienced in children's worship. First, it deals with the meaning of religious, aesthetic, and communal driving forces that children can experience in children's worship, focusing on Eberhard's research. In addition, it deals with the meaning of language and expression methods provided in children's worship, and finally, it says that children's worship can be a space where you can experience stability and coziness. Through this, it is emphasized that children's worship can play an important role in supporting the personal development of children living in modern times.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.3
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• pp.249-254
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• 2023

La_0.7-xCe_xSr_0.3MnO₃ specimens were fabricated by a solid state reaction method and structural and electrical properties with variation of Ce⁴⁺ contents were measured. All specimens exhibited a polycrystalline rhombohedral crystal structure, and the (110) peaks were shifted to low angle side with increasing the amount of Ce⁴⁺ contents. As Ce⁴⁺ ions with different ion radii and charges are substituted with La³⁺ ions, electrical properties are thought to be affected by changes in the double exchange interaction between Mn³⁺-Mn⁴⁺ ions due to distortion of the unit lattice, a decrease in oxygen vacancy concentration, and an increase in lattice defects. Resistivity gradually decrease as the amount of Ce⁴⁺ added increased, and negative temperature coefficient of resistance (NTCR) properties were shown in all specimens. In the La_0.5Ce_0.2Sr_0.3MnO₃ specimens, electrical resistivity, TCR and B-value were 31.8 Ω-cm, 0.55%/℃ and 605 K, respectively.