• Earthquakes and Structures
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• 제26권6호
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• pp.417-431
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• 2024

The fundamental period of vibration is one of the most critical parameters in the analysis and design of structures, as it depends on the distribution of stiffness and mass within the structure. Therefore, building codes propose empirical equations based on the observed periods of actual buildings during seismic events and ambient vibration tests. However, despite the fact that infill walls increase the stiffness and mass of the structure, causing significant changes in the fundamental period, most of these equations do not account for the presence of infills walls in the structure. Typically, these equations are dependent on both the structural system type and building height. The different values between the empirical and analytical periods are due to the elimination of non-structural effects in the analytical methods. Therefore, the presence of non-structural elements, such as infill panels, should be carefully considered. Another critical factor influencing the fundamental period is the effect of Soil-Structure Interaction (SSI). Most seismic building design codes generally consider SSI to be beneficial to the structural system under seismic loading, as it increases the fundamental period and leads to higher damping of the system. Recent case studies and postseismic observations suggest that SSI can have detrimental effects, and neglecting its impact could lead to unsafe design, especially for structures located on soft soil. The current research focuses on investigating the effect of infill panels on the fundamental period of moment-resisting and eccentrically braced steel frames while considering the influence of soil-structure interaction. To achieve this, the effects of building height, infill wall stiffness, infill openings and soil structure interactions were studied using 3, 6, 9, 12, 15 and 18-story 3-D frames. These frames were modeled and analyzed using SeismoStruct software. The calculated values of the fundamental period were then compared with those obtained from the proposed equation in the seismic code. The results indicate that changing the number of stories and the soil type significantly affects the fundamental period of structures. Moreover, as the percentage of infill openings increases, the fundamental period of the structure increases almost linearly. Additionally, soil-structure interaction strongly affects the fundamental periods of structures, especially for more flexible soils. This effect is more pronounced when the infill wall stiffness is higher. In conclusion, new equations are proposed for predicting the fundamental periods of Moment Resisting Frame (MRF) and Eccentrically Braced Frame (EBF) buildings. These equations are functions of various parameters, including building height, modulus of elasticity, infill wall thickness, infill wall percentage, and soil types.

• 통상정보연구
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• 제14권1호
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• pp.171-195
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• 2012

본 논문은 한중 양국의 FDI 관련 현황과 정책적 강약점을 파악하고 이를 통해 중국자본 유치전략에서 요구되는 기본적 전제조건을 검토함으로써 향후 중국자본 유치에 도움이 되는 정책방향을 모색하는 데에 연구목적을 둔다. 연구결과 도출된 주요 전제조건들을 제시하면 다음과 같다. 첫째, 한중간 경제관계는 상호보완적이고도 협력적인 수준에 크게 미흡한 상태이므로 무조건적 경쟁관계로 발전할 수 있는 위협요인들을 미리 제거하고, 양국간 신뢰관계를 확대해 나가야 한다. 둘째, 적어도 중국의 입장에서 보면 한국은 매력적인 투자처가 되지 못하고 있다. 최근 발효된 한미FTA 등 한국의 FTA 확대 기회를 적극 활용할 필요가 있다. 셋째, 한국을 대신하는 중국의 대체투자처는 항상 존재하고 있으므로, 투자종목이나 투자규모, 투자방식 등 중국자본 유치에 관련된 투자 협상력은 상당 부분 중국측이 가지고 있다는 사실을 간과하지 말아야 할 것이다. 넷째, 한국의 FDI 정책이 기존의 정책적 프레임 속에 갇혀 규칙 파괴자(rule breaker)의 기능을 발휘하지 못한다면 중국자본 유치는 노력에 비해 성과를 기대하기 어려울 것이다. 다섯째, 중국을 과대평가하거나 중국자본의 힘을 맹신하는 상황에서 중국자본 유치 노력을 경주하다가는 외형적 투자 또는 부실투자로 이어져 예기하지 못한 국가적 손실을 초래할 수 있다는 점에 유의해야 한다.

• 가정과삶의질연구
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• 제2권1호
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• pp.93-109
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• 1984

The purpose of this study is to investigate the direction and strategy of education for sex role concepts of children on the basis of factor analysis of the present situation in sex role concepts and their formation. Although some maintain that sex role concept of our society has been changing slowly, the traditional sex role concept still dominates and is potentially immanent. the analysis of present condition of our society indicates that the formal as well as informal education are facing with various crucial problems in providing the direction of behavior demanded for carrying out the role. The close analysis of the three theories, psychoanalytic theory , social learning theory, cognitive development theory, lends a support to the laim of the study that cognitive development theory provide an integrated frame of reference for us to see the sex role education analytically Furthermore, the factors which are found to have influences on the formation of sex role have been analyzed in three areas: Family, School and society. 1)The factors in family such as parental behavior of upbringing and their concepts of sex role have a direct relationship with the nature of sex tole concept of children. Therefore, the first step to make children to habe a new type of sex-role conception appropriate for modern societies is to change that of parental conception and attitudes. 2)the quantitative as well as the qualitative aspects of school education showed no exceptional trend from the dominant conception of the society, although school are expected to lead the society as formal education institution rather than just reflect the society. The educational activities and contents such as the conceived goal of education for eoch sex, textbook constitation, teaching behavior and sex-role concepts of teacher are found to be still dominated by the traditional sex-role assumption. 3) The social factors that have direct relationship with children's sex-role formation are social and cultural, which include social milieu, condition of employment, family structure and mass-media. Since family and school do not educate the young in a social vacuum. their educational function of sex-role formation are doomed to be limited and determined by these social factors. Unfortunately, the analysis of present conditions showed the dominance of traditional types of sex-role concepts in all these social factors. The education of sex-role concept for children should be treated as one of the most crucial value problems related with many other important problems, such as direction and patterns of behaviors of each sex, the degree of self-development and capabilities, and consequently human right, equality, humanization and the quality of happiness. Neverthless, the analysis of researches on sex-role education which have been surveyed in this study lead to a conclusion that concerted effort to change the education, formal as well as informal should be provided in every aspect of social life. If the sex role education of the past has aimed at the "feminization"of girls which indoctrinate girls into a limited and fixed role of house wives, the new education in the future should be directed foward "humanization" of both sexes which opens the diversity of roles for both boys and girl on equal levels and provide future possibilities in accordance to their individual capabilities and interests.

• Steel and Composite Structures
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• 제5권2_3호
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• pp.181-192
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• 2005

The effective length method for flexural (column) buckling has been used for many decades but its use is somewhat limited in various contemporary design codes to moderately slender structures with elastic critical load factor (${\lambda}_{cr}$) less than 3 to 5. In pace with the use of higher grade steel in recent years, the influence of buckling in axial buckling resistance of a column becomes more important and the over-simplified assumption of effective length factor can lead to an unsafe, an uneconomical or a both unsafe and uneconomical solution when some members are over-designed while key elements are under-designed. Effective length should not normally be taken as the distance between nodes multiplied by an arbitrary factor like 0.85, 1.0, 2.0 etc. Further, the classification of non-sway and sway-sensitive frames makes the conventional design procedure tedious to use and, more importantly, limited to simple regular frames. This paper describes the practical use of second-order analysis with section capacity check allowing for $P-{\delta}$ and $P-{\Delta}$ effects together with member and system imperfections. Most commercial software considers only the $P-{\Delta}$ effect, but not member and frame imperfections nor $P-{\delta}$ effect, and engineers must be very careful in their uses. A verification problem is also given for validation of software for this type of powerful second-order analysis and design. It is a trend for popular and advanced national design codes in using the second-order analysis as a norm for analysis and design of steel structures while linear analysis may only be used in very simple structures.

• Earthquakes and Structures
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• 제14권1호
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• pp.1-10
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• 2018

Seismic retrofitting of existing buildings and design of earth-quake resistant buildings are important issues associated with earthquake-prone zones. Use of metallic-yielding dampers as an energy dissipation system is an acceptable method for controlling damages in structures and improving their seismic performance. In this study, the optimal distribution of dampers for reducing the seismic response of steel frames with multi-degrees freedom is presented utilizing the uniform distribution of deformations. This has been done in a way that, the final configuration of dampers in the frames lead to minimum weight while satisfying the performance criteria. It is shown that such a structure has an optimum seismic performance, in which the maximum structure capacity is used. Then the genetic algorithm which is an evolutionary optimization method is used for optimal arrangement of the steel dampers in the structure. In continuation for specifying the optimal accurate response, the local search algorithm based on the gradient concept has been selected. In this research the introduced optimization methods are used for optimal retrofitting in the moment-resisting frame with inelastic behavior and initial weakness in design. Ultimately the optimal configuration of dampers over the height of building specified and by comparing the results of the uniform deformation method with those of the genetic algorithm, the validity of the uniform deformation method in terms of accuracy, Time Speed Optimization and the simplicity of the theory have been proven.

• Steel and Composite Structures
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• 제36권4호
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• pp.383-398
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• 2020

This paper investigates the progressive collapse behavior of 3D steel-framed gravity buildings under fires with a cooling phase. The effect of fire protections and bracing systems on whether, how, and when a gravity building collapses is studied. It is found that whether a building collapses or not depends on the duration of the heating phase, and it may withstand a "short-hot" fire, but collapses under a mild fire or a "long-cool" fire. The collapse time can be conservatively determined by the time when the temperature of steel columns reaches a critical temperature of 550 ℃. It is also found that the application of a higher level of fire protection may prevent the collapse of a building, but may also lead to its collapse in the cooling phase due to the delayed temperature increment in the heated members. The tensile membrane action in a heated slab can be resisted by a tensile ring around its perimeter or by tensile yielding lines extended to the edge of the frame. It is recommended for practical design that hat bracing systems should be arranged on the whole top floor, and a combination of perimeter and internal vertical bracing systems be used to mitigate the fire-induced collapse of gravity buildings. It is also suggested that beam-to-column connections should be designed to resist high tensile forces (up to yielding force) during the cooling phase of a fire.

• 조명전기설비학회논문지
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• 제29권3호
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• pp.39-44
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• 2015

Optical characteristics including the radiant flux and viewing angle of UV LEDs were investigated according to both silicone encapsulants with different refractive indexes and lens shapes. Lead frame was fabricated using the enhanced heat dissipation characteristics with a heat slug structure and the reflector based on EMC(Epoxy Mold Compound) material. Four types of lens shapes were designed and their optical characteristics depending on the refractive index of silicone encapsulants were evaluated. The maximum radiant flux can be achieved when the height of lens are 1.32mm and 1.08mm for silicone encapsulants with low and high refractive indexes, respectively. Depending on the encapsulating method, the viewing angle changes from $148.9^{\circ}$ to $130.2^{\circ}$ for low refractive index and from $145.3^{\circ}$ to $136.8^{\circ}$ for high refractive index. As a result, it is found that the optical characteristics of UV LEDs can be controled through both encapsulating method and the refractive index of encapsulants.

• 한국가스학회지
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• 제21권5호
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• pp.77-82
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• 2017

노후화 된 공정설비와 공장의 규모 확대 등 유해화학물질 사용량이 증가하고 있으며, 2013년부터 지속적으로 누출에 의한 사고가 발생하는 것을 확인할 수 있다. 장외영향평가에서 누출에 대한 끝점 농도는 ERPG 2로 나타내며, 안전보건공단의 가이드에서 시간에 따라 7분 미만에서 10분의 AEGL 2, 7분 이상 25분 미만일 때는 30분의 AEGL 2값을 사용한다. 기준이 되는 끝점 농도가 시간에 따라 모호하게 사용되고 있어, 사고 발생 시 문제를 야기할 것으로 생각이 된다. 이에 본 연구에서 회귀곡선을 통해 1~10분 사이의 AEGL 값을 도출하고, 동 시간의 Probit function의 0% Lethality 데이터와 비교하였으며, AEGL 결과 값을 사용하여 보다 명확한 시간에 따른 독성누출 평가에 활용될 것으로 생각된다.

• 한국콘텐츠학회논문지
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• 제17권7호
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• pp.79-92
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• 2017

본 연구의 목적은 2013년에 방영된 '조기영어교육 열풍, 신음하는 아이들' 시사다큐멘터리의 서사구조를 Chatman(2003)의 모형으로 분석하는 것이다. 통합체 분석을 위해 사건의 전개에 초점을 맞추어 이야기의 내용 흐름을 탐색하고, 계열체 분석을 통해서는 텍스트에 잠재되어 있는 이항대립 구조를 분석했다. 해당 방송은 '균형-혼란-재균형'의 서사 구조를 바탕으로, 영어 몰입교육 금지에 따른 혼란의 상황이 영어 사교육 시장을 확장시켰으며, 학생들의 영어학습이 점점 앞당겨지는 상황이 발생했고, 그로 인해 새로운 해결책을 모색할 수밖에 없다는 내용으로 전개시켰다. 그러나 조기 영어교육의 열풍을 유발했다는 정부의 목소리는 제대로 등장하지 않고, 피해자로 위치화된 학생들의 모습도 구체적으로 묘사되어 있지 않은채, 학부모, 사립초등학교 관계자, 영어학원 관계자들이 조기 영어교육의 열풍과 영어 몰입교육의 행위를 유발하는 핵심 주체로 등장하고 있다. 또한 조기 영어교육 열풍을 잠재울 해결안으로 정서적 단면, 교수 방법적 차이 등을 다루면서 보다 중층적인 진단과 대안을 모색하지 못했다.

• Earthquakes and Structures
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• 제15권5호
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• pp.453-462
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• 2018

Damages to buildings affected by a near-fault strong ground motion are largely attributed to the vertical component of the earthquake resulting in column failures, which could lead to disproportionate building catastrophic collapse in a progressive fashion. Recently, considerable interests are awakening to study effects of earthquake vertical components on structural responses. In this study, detailed modeling and time-history analyses of a 12-story code-conforming reinforced concrete moment frame building carrying the gravity loads, and exposed to once only the horizontal component of, and second time simultaneously the horizontal and vertical components of an ensemble of far-field and near-field earthquakes are conducted. Structural responses inclusive of tension, compression and its fluctuations in columns, the ratio of shear demand to capacity in columns and peak mid-span moment demand in beams are compared with and without the presence of the vertical component of earthquake records. The influences of the existence of earthquake vertical component in both exterior and interior spans are separately studied. Thereafter, the correlation between the increase of demands induced by the vertical component of the earthquake and the ratio of a set of earthquake record characteristic parameters is investigated. It is shown that uplift initiation and the magnitude of tensile forces developed in corner columns are relatively more critical. Presence of vertical component of earthquake leads to a drop in minimum compressive force and initiation of tension in columns. The magnitude of this reduction in the most critical case is recorded on average 84% under near-fault ground motions. Besides, the presence of earthquake vertical components increases the shear capacity required in columns, which is at most 31%. In the best case, a direct correlation of 95% between the increase of the maximum compressive force and the ratio of vertical to horizontal 'effective peak acceleration (EPA)' is observed.