• Structural Engineering and Mechanics
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• 제55권1호
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• pp.229-244
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• 2015

H-infinity norm relates to the maximum in the frequency response function and H-infinity control method focuses on the case that the vibration is excited at the fundamental frequency, while 2-norm relates to the output energy of systems with the input of pulses or white noises and 2-norm control method weighs the overall vibration performance of systems. The trade-off between the performance in frequency-domain and that in time-domain may be achieved by integrating two indices in the mixed vibration control method. Based on the linear fractional state space representation in the modal space for a piezoelectric flexible structure with uncertain modal parameters and un-modeled residual high-frequency modes, a mixed dynamic output feedback control design method is proposed to suppress the structural vibration. Using the linear matrix inequality (LMI) technique, the initial populations are generated by the designing of robust control laws with different H-infinity performance indices before the robust 2-norm performance index of the closed-loop system is included in the fitness function of optimization. A flexible beam structure with a piezoelectric sensor and a piezoelectric actuator are used as the subject for numerical studies. Compared with the velocity feedback control method, the numerical simulation results show the effectiveness of the proposed method.

• 한국소음진동공학회논문집
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• 제16권6호
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• pp.619-626
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• 2006

Body-on-frame type vehicle has a set of frame bushes between body and frame for vibration isolation. Such frame bushes are important vibration transmission paths to passenger space for excitations during driving. In order to reduce the vibration level of passenger space, therefore, change of complex stiffness of the frame bushes is more efficient than modification of other parts of the vehicle such as body, frame and suspension. The purpose of this study is to reduce the vibration level for ride comfort by optimization of complex stiffness of frame bushes. In order to do this, a simple finite element vehicle model was constructed and complex stiffness of the frame bushes was set to be design variables. The objective function was defined to reflect frequency dependence of passenger ride comfort. Genetic algorithm and sub-structure synthesis were applied for minimization of the objective function. After optimization level at a position of interest on the car body was reduced by about 43.7 % in RMS value. Causes for optimization results are discussed.

• 수산경영론집
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• 제31권1호
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• pp.1-12
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• 2000

The experience of many countries strongly suggests that bad governments and institutions have been a serious, if not the most serious, obstacle to economic growth and industry-structural adjustments. All public sectors pursue a mix of both predatory and productive activities-bad governments emphasizing the former, while good governments finding a way of promoting the later. In fishery public policy studies, much confusion exists about the roles of policy illustration and prescription. In general fishery public sectors involve collective actions by numerous individuals under conditions of uncertainty, complexity, bounded rationality, and imperfect information structure. All collective fisheries action organizations consist of a center(e.g., government), which leads fishery group actions, and peripheral participants(e.g., fishermen), which are controlled by the government. A paradigm is developed that gives both theoretical and empirical meaning to the constitutional determination of fisheries political preference function or fishery public sector governance structures. Three relevant spaces are specified: policy instrument, results, and constitutional. The collective-choice rules of the constitutional space structure the tradeoff between public and special fishery interest groups. Fishery public sectors seeking sustainable reductions in wasteful rent-seeking fishing activities should select constitutional principles and institutional structures that tend to promote resource sustainability. In particular, the effects of internal and external events on fisheries may result in a greater or lesser concentration of interest group power. Thus, the structure of the fishereis political power must be assessed in any prescriptive evaluation of alternative fishery governance weights.

• Journal of Computing Science and Engineering
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• 제9권1호
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• pp.1-8
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• 2015

Accessing and searching in a sequence of numbers are fundamental operations in computing that are encountered in a wide range of applications. One of the applications of the problem is cryptanalytic time-memory tradeoff which is aimed at a one-way function. A rainbow table, which is a common method for the time-memory tradeoff, contains elements from an input domain of a hash function that are normally sorted integers. In this paper, we present a practical indexing method for a monotonically increasing static sequence of numbers where the access and search queries can be addressed efficiently in terms of both time and space complexity. For a sequence of n numbers from a universe $U=\{0,{\ldots},m-1\}$, our data structure requires n lg(m/n) + O(n) bits with constant average running time for both access and search queries. We also give an analysis of the time and space complexities of the data structure, supported by experiments with rainbow tables.

• 한국응용곤충학회지
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• 제40권2호
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• pp.155-196
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• 2001

Basically insect hormones include ecdysteroids (molting hormone), juvenile hormones, and neurohormones comprising neuropeptides and biogenic amines. This article reviewed their chemical structures and biological functions. The active molting hormone is 20-hydroxyecdysone in most insects but makisterone A in some other insects including the honey bee and several phytophagous hemipterans. Most insects use JH III, but lepidopterans JH I and II. Dipterans also use a different JH, so-called JH $B_3$(JH III bisepoxide) and we still do not know the exact chemical structure of JH utilized in hemipterans. Some other insects use methyl farnesoate or hydroxylated JH III analogues as their juvenile hormone. Most diverse pictures can be found in neurohormones (NH), especially in neuropeptides, in terms of their number and structure. There are more than 200 neuropeptides (NP), classified into more than 30 families, which structures have been identified, and more of them are expected to be reported in the near future, partly due to rapid development in molecular biological techniques and in analytical techniques. More than half of them are involved in controlling activity of visceral muscles. But function (s) of many NPs are not clarified yet, even though their amino acid sequences have been identified. It is partly due to the fact that a single NP may have multiple functions. Another interesting point is their gene structure, having many number of independent, active peptides in one gene, apparently working for similar or totally different functions. NH also includes amines, such as octopamine, dopamine, serotonin, etc. From now on, investigation will be concentrated on identifying their function (s) and receptors, and on possibilities of their utilization as control agents against pest insects.

• 대한기계학회논문집
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• 제17권1호
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• pp.62-68
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• 1993

본 연구에서는 장섬유강화 고분자복합판을 고온압축성형할 때 섬유의 분리 및 배향은 서로 불가분의 관계가 있으므로, 모재와 섬유의 분리에 의해서 야기되는 성형 품의 불균질성을 나타내는 균질도와 섬유의 배향을 표시하는 배향함수와의 상관관계에 대한 실험결과를 보고한다.

• Structural Engineering and Mechanics
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• 제63권1호
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• pp.115-124
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• 2017

In this paper, a different technique to predict the effects of soil-structure interaction (SSI) on seismic response of building systems is investigated. The technique use a machine learning algorithm called Support Vector Regression (SVR) with technical and analytical results as input features. Normally, the effects of SSI on seismic response of existing building systems can be identified by different types of large data sets. Therefore, predicting and estimating the seismic response of building is a difficult task. It is possible to approximate a real valued function of the seismic response and make accurate investing choices regarding the design of building system and reduce the risk involved, by giving the right experimental and/or numerical data to a machine learning regression, such as SVR. The seismic response of both single-degree-of-freedom system and six-storey RC frame which can be represent of a broad range of existing structures, is estimated using proposed SVR model, while allowing flexibility of the soil-foundation system and SSI effects. The seismic response of both single-degree-of-freedom system and six-storey RC frame which can be represent of a broad range of existing structures, is estimated using proposed SVR model, while allowing flexibility of the soil-foundation system and SSI effects. The results show that the performance of the technique can be predicted by reducing the number of real data input features. Further, performance enhancement was achieved by optimizing the RBF kernel and SVR parameters through grid search.

• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.673-675
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• 2004

The tetranuclear copper(II) cluster compound $[Cu_4OCl_6(C_{14}H_{12}N_2)_4]$ has been synthesized by hydrothermal reaction and studied by X-ray diffraction. The four copper(II) atoms locate four capsheaves of a tetrahedral skeletal structure and a oxygen atom as interstitial atom occupies the center position of the same tetrahedron, and each edge of the Cu-Cu tetrahedron is bridged by one ${\mu}_2$-Cl anion. The copper atom possesses slightly distorted trigonal bipyramidal geometry with three ${\mu}_2$-Cl atoms in equatorial position and the interstitial O atom and one N atom from 3-benzyl-benzimidazole ligand occupying axial position. The Cu-Cu distances are in the range of 3.0986-3.1162 ${\AA}$. The EPR spectrum suggested that the copper(II) ground state $d_{x2-y2}$ and the coordination geometry was trigonal bipyramidal.

• 한국실내디자인학회논문집
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• 제6호
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• pp.53-62
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• 1995

This research aims at proving the fact that the forms, spaces and many other design concepts of Modernism are much related with the changes of materials, struc-tures, and the way of construction as well as the idealis-tic and aesthestic things through the history of steel, one of the most important materials of the style. The meaning steel has in the modern architecture can be studied in the structure and industrial production system. 1) Steel frame broadened the range of understanding the space and created the new form through the skeleton/skin structure by reinterpreting the existing space fac-tors while it was being adopted to the architecture. Walls could be freed from the traditional function of bear-ing wall and roofs gave the transparancy to the interior by being linked with the glass. Posts lost the function which confines the space in the frame of the grid system and gave the flexibility to the interior due to the economical materials. These changes made the movable partition, screen with various materials and the system furniture which divides the space more important. 2) In the aspect of the industrialized architecture, it be-came the moment that the most of the archtectural com-posing parts were in mass production as they were standarized, high qualified, and generalized by the indus-trial characteristics of steel, and the specialization of structure and cladding, but the neither of the efforts to make the building itself by mass production or to standarize it was fulfilled. The high-tech architecture which borrows its archtectural manifestation from the high technology, however, is consistently paying efforts on such industrialization.

• 한국자동차공학회논문집
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• 제12권3호
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• pp.109-121
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• 2004

This paper presents an optimal design method for structure-borne durability of a vehicle body structure. Structure-borne durability design requires a new design that can increase fatigue lives of critical areas in a structure and must prohibit transition phenomenon of critical areas that results from modification of the structure at the same time. Therefore, the optimization problem fur structure-borne durability design are consists of an objective function and design constraints of 2 types; type 1-constraint that increases fatigue lives of the critical areas to the required design limits and type 2-constraint that prohibits transition phenomenon of critical areas. The durability design problem is generally dynamic because a designer must consider the dynamic behavior such as fatigue analyses according to the structure modification during the optimal design process. This design scheme, however, requires such high computational cost that the design method cannot be applicable. For the purpose of efficiency of the durability design, we presents a method which carry out the equivalent static design problem instead of the dynamic one. In the proposed method, dynamic design constraints for fatigue life, are replaced to the equivalent static design constraints for stress/strain coefficients. The equivalent static design constraints are computed from static or eigen-value analyses. We carry out an optimal design for structure-borne durability of the newly developed bus and verify the effectiveness of the proposed method by examination of the result.