• Structural Engineering and Mechanics
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• v.75 no.5
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• pp.541-557
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• 2020

A novel family of controllable, dissipative structure-dependent integration methods is derived from an eigen-based theory, where the concept of the eigenmode can give a solid theoretical basis for the feasibility of this type of integration methods. In fact, the concepts of eigen-decomposition and modal superposition are involved in solving a multiple degree of freedom system. The total solution of a coupled equation of motion consists of each modal solution of the uncoupled equation of motion. Hence, an eigen-dependent integration method is proposed to solve each modal equation of motion and an approximate solution can be yielded via modal superposition with only the first few modes of interest for inertial problems. All the eigen-dependent integration methods combine to form a structure-dependent integration method. Some key assumptions and new techniques are combined to successfully develop this family of integration methods. In addition, this family of integration methods can be either explicitly or implicitly implemented. Except for stability property, both explicit and implicit implementations have almost the same numerical properties. An explicit implementation is more computationally efficient than for an implicit implementation since it can combine unconditional stability and explicit formulation simultaneously. As a result, an explicit implementation is preferred over an implicit implementation. This family of integration methods can have the same numerical properties as those of the WBZ-α method for linear elastic systems. Besides, its stability and accuracy performance for solving nonlinear systems is also almost the same as those of the WBZ-α method. It is evident from numerical experiments that an explicit implementation of this family of integration methods can save many computational efforts when compared to conventional implicit methods, such as the WBZ-α method.

• Journal of Animal Environmental Science
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• v.19 no.2
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• pp.183-190
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• 2013

Establishment of a new concept of environmental friendly livestock manure management is required based on the facts. But now liquid fertilizer quality in korea shows a large difference among regions and the regulations are uncertain. Focusing on precedent study on main level-grading factors of liquid fertilizer quality certification, the study collected laws and standards related to liquid fertilizer of livestock manure at home and abroad and produced evaluation standards. Liquid fertilizer was divided into four factors (fertilizing value, harmfulness, stability and uniformity). According to each item, scores were awarded based on 16 details: fertilizing value (Nitrogen concentration, the whole concentration of Nitrogen, Phosphoric acid and Kalium), harmfulness (heavy metals, pathogenic microorganism and antibiotics), stability (maturity degree and odour), uniformity (EC, BOD, SS, moisture content and salt). The grade of liquid fertilizer, A (42~48), B (34~41), C (26~33) were rated using total scores.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.373-377
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• 2002

In this study, we suggested a slim-type actuator that can be controlled in radial direction for compensating coma aberration in high-capacity optical storage devices. To deal successfully with narrow space in slim-type optical pick-up for notebook pc device, additional yokes for tilting motion are integrated into main yoke of the actuator. And the location of tilting coils is determined for mass-b3lancing effect to achieve optimal configuration for high driving sensitivity. We also suggested new concept of lens holder to guarantee excellent stability of control system by enhancing the gain margin at secondary resonant frequency. The concept was realized by forming damping sections in the lens holder, which prevent vibrational energy from transferring to lens. An exclusive measurement system was newly developed for fast and precise measurement of dynamic characteristics of actuators and utilized for the practical use. We hope to make good use of this system also in time to come.

• KIEAE Journal
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• v.2 no.2
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• pp.23-31
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• 2002

The purpose of this study is to suggest an environmentally friendly energy system of ecological architecture, with the reference to foreign cases, judge feasibility of it. The ecological architecture is very similar to the natural ecosystem. There is growing international scientific consensus that human activities are having a discernible effect on the global climate. Therefore, with a precise understanding of the concept of ecological approach and concrete perception of the necessity it, an establishment of planning which recognizes the ecological architecture as a organism a same time, ensures diversity, stability and cycling stemmed from the ecosystem to various activities through a ecological structure shall bring the introduction of substantial ecological architecture into domestic realm. As a result, in this Age of industrial science, We are proposing useful materials and suggestion regarding the ecological architecture planning of korean cities, by preestimating the characteristics of a city heading toward the Age of the new ecological environment.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.100-100
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• 2016

Among various two-dimensional (2D) materials, 2D semiconductors and insulators have attracted a great deal of interest from nanoscience community beyond graphene, due to their attractive and unique properties. Such excellent characteristics have triggered highly active researches on 2D materials, such as hexagonal boron nitride (hBN), molybdenum disulfide (MoS2), and tungsten diselenide (WSe2). New physics observed in 2D semiconductors allow for development of new-concept devices. Especially, these emerging 2D materials are promising candidates for flexible and transparent electronics. Recently, van der Waals heterostructures (vdWH) have been achieved by putting these 2D materials onto another, in the similar way to build Lego blocks. This enables us to investigate intrinsic physical properties of atomically-sharp heterostructure interfaces and fabricate high performance optoelectronic devices for advanced applications. In this talk, fundamental properties of various 2D materials will be introduced, including growth technique and influence of defects on properties of 2D materials. We also fabricate high performance electronic/optoelectronic devices of vdWH, such as transistors, memories, and solar cells. The device platform based on van der Waals heterostructures show huge improvement of devices performance, high stability and transparency/flexibility due to unique properties of 2D materials and ultra-sharp heterointerfaces. Our work paves a new way toward future advanced electronics based on 2D materials.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.10 no.1
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• pp.61-69
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• 2006

SSO (Single Sign On), which allows users to have an access to a various systems through a single authentication, has been receiving much attention from many enterprises due to the user convience through a single authentication and the recent security features based on PKI. An emerging authentication management system called EAM has further enhanced the efficiency and stability of the enterprise IT infrastructrure systems. In this article, the basic concept and characteristics of the existing SSO systems are analyzed and a new SSO model, based on PKI where authentication load is balanced via multiple circulators, is presented.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.767-770
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• 1991

For the control of redundant manipulators, conventional dynamic control methods of local torque optimization showed the instability which resulted in physically unrealizable torque requirements. In this paper, a new dynamic control method which is based on the concept of aspects is proposed. The proposed method starts with the basic understanding of the minors in the Jacobian matrix. It was shown by computer simulations that the proposed method demonstrates a drastic reduction of torque loadings at the joints in the tracking motion of a long trajectory, and thus guarantees the stability of joint torque.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.29 no.2
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• pp.55-66
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• 2021

ICAO recommended that airspace monitoring and periodic safety assessments in each Contracting State ensure the stability of the airspace, since reducing the aircraft lateral and vertical separation intervals would rather increase the risk of collision. The target level of safety of the AKARA-FUKUE Corridor at the southern end of Jeju was 247×10^-9. In simple comparison, this means that the risk of an aircraft collision in this area (international safety standards, 5.0×10^-9) is about 50 times higher. The scope of this study is to organize the concept of terms, analyze the air traffic volume, the current status of navigational safety facility usage fees, and investigations of an aircraft collision risk in Jeju southern air corridor. Analyzing government policies and overseas evaluations, revising some of the existing contents, presenting some of the additional contents of new routes, and changing the instrument procedure for Korean-Chinese routes, change of arrive/departure route between Incheon Airport and Shanghai Airport, reduce the risk of aircraft collisions. We hope to restore airspace sovereignty, contribute to policies for the government to take the lead in solving this problem, and expect stability and operational efficiency in air traffic.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.7
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• pp.98-104
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• 2004

A spacecraft alignment measurement requires highly precise measurement accuracy which is less than ${\pm}0.5^{\circ}$. In general, such an alignment measurement has been performed by using three or more theodolites. However, it contains the latent accuracy error because of a position stability of spacecraft, etc. The new alignment measurement system which consists of a theodoilte, a rotating table and a digital inclinometer has been developed to possibly to possibly reduce the error. This paper describes the concept and methodology of methodology of measurement system. It was found that new measurement system can provide more accurate results than the conventional system.

• Journal of the Korean Society of Costume
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• v.40
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• pp.51-65
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• 1998

In this study the features expressed by the Korean dresses and its ornaments have been examined through the objects of this thesis, the concept of the pair, under the basis of Korean myths, from which esthetic and spiritual values have been derived. At first, the beauty of the balance pursuing the neatness. Since the pair is made with two piecess, at the time of the placement, the sense of the balance is obtained by the arrangement acccording to the dichotomous principle such as up and down or left and right. Sometimes, the pair could yield the natural pictorial composition, but almost of the time symmetrical composition. This kind of composition is made symmetrical like the structure of the human body, and it is resulted in a neat beauty, which visually presents a harmony, stability and intimacy. At second, the beauty of the harmony in the spirit of the oneness. From the dualistic combination basing on Korean myths, the common features and the significance of the co-existence, obtained from the combination of the pair of the pieces, could be found. By the oneness of the both elements, the creation principle, which is the basic one for a new life, could be established, and the mystery of the creation and the sense of the harmony could be found in it. At third, the wholeness of the completeness concept. The completeness could be felt rather by two than by one, and is provided with a room to be filled with the other one. Consequently, the outer dress is completed with the under dress, and its own beauty could only be made out when the two elements are harmonized. So, it is called as the pair. Like this, the concept about the pair taken roots in the ground of Korean emotions, is basing on the creation principle of the dualistic elements formed from the tradition of Korean myths, and the fact that the mental meaning pursuing the harmony dwells in Korean dress and its ornaments could be confirmed.