• Title/Summary/Keyword: 구조적 붕괴

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The Effect of Dealumination on the Structure and Acidity of SAPO-11 Molecular Sieve (탈알루미늄화가 SAPO-11 분자체의 구조 및 산성도에 미치는 영향)

  • Park, Jong Yul;Lee, Chi Hun;Kim, Soo Kyung
    • Journal of the Korean Chemical Society
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    • v.40 no.3
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    • pp.202-208
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    • 1996
  • SAPO-11 was synthesized hydrothermally and dealuminated with $H_4$EDTA. The framework structure of SAPO-11 was maintained safely by 24 hours' dealumination, but further dealumination for 48 hours caused SAPO-11 collapsed and to be changed to variscite($AIPO_4{\cdot}2H_2O$) and tridymite($SiO_2$). Dealuminated SAPO-11 showed two structural hydroxyl bands at 3607 $cm^{-1}$ and 3453 $cm^{-1}$ respectively. The intensities of these two bands increased according to the extent of dealumination, and disappeared by the adsorption of methylamine. Dealuminated SAPO-11 showed higher desorption temperatures and greater activation energies in desorption of water and methylamine compared to non-dealuminated SAPO-11. All the phenomena may be due to the stronger interactions of Bronsted acid sites of structural hydroxyl groups generated by dealumination with adsorbed water and methylamine molecules respectively.

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Slab Effect on Inelastic Behaviors of High Strength RC Beam-Column Joints (고강도 RC 보-기둥 접합부의 비탄성 거동에 대한 슬래브의 영향)

  • 장극관;김윤일;오영훈
    • Magazine of the Korea Concrete Institute
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    • v.9 no.2
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    • pp.167-177
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    • 1997
  • In thtx design of ductile moment -1csist1ng frnmcls (DMRFs) f'ollow~ng the. stlong columnweakbeam design philosophy, it is desirable that the joint and column remain essentiallyelastic in order to insure proper energy dissipation and lateral stability of the structure.Thv joint has been identifid as the "weak link: in DMRFs because any stiffness orstrength deterioration in this region can lead to substantial drifts and the possibility ofcollapse due to t'-delta effects. h3oreove1.. the tngintw is faced with the difficult task ofdetailing an element whose size is determined by theframing members, but \vhich mustresist a set of loads very different from those used in the design of the beams and columns.Four 3 -scale beam-column-slab joint assemblies were designed according to existing cod\ulcornerrequirements of' ACI 318-89. representing perimeter joints of DMRFs with reinforced highstrength concrete. The influence on aseismic behavior of beam-column joints due tomonolithic slab, has been investigated.lab, has been investigated.

The Development of Compressive Strength Estimation Equation for LNG Storage Tank using Rebound Hardness Method (반발경도법을 이용한 LNG 저장탱크 콘크리트의 압축강도 추정식 개발)

  • Kim, Jung-Hoon;Kim, Young-Gu;Jo, Young-Do
    • Journal of the Korean Institute of Gas
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    • v.21 no.3
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    • pp.26-32
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    • 2017
  • Outer tank concretes of LNG storage tank are composed of prestressed concrete structures that act as a protective wall. The danger such as the collapse of structures will exist if concrete structures is not secured due to the deterioration. Concrete compressive strength directly related to the safety of structures can be predicted by using estimation equation of compressive strength through rebound hardness test and ultrasonic wave velocity method. But, there is no the estimation equation of LNG storage tank for a relation between NDT data and real strength. In this study, to obtain more accurate real strengths for LNG storage tank, core specimens were sampled from walls of pilot LNG storage tank. The rebound hardness test of general NDT for concrete structures was carried out at each 3 positions for the four areas. The compressive strength estimation equation of LNG storage tank was developed by using the data for rebound hardness test of pilot LNG storage tank and compressive strength test of sampled concrete cores.

Seismic Behavior Characteristics of Ground Storage Circular Tanks and Proposal of Performance-based Seismic Design Method (평저형 원형 저장탱크의 지진거동 특성 및 성능기반 내진설계법 제안)

  • Han dong yun;Sun chang ho;Kim ick hyun;Nam, hyung mo
    • Journal of the Korean Institute of Gas
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    • v.27 no.4
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    • pp.34-42
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    • 2023
  • Considering the contribution of industrial facilities to the national economy, securing operability against earthquakes is very important. However, the basic concept of current seismic design mainly allows ductile behavior of facilities against large-scale earthquakes and only considers structural safety for the purpose of preventing collapse. In order to secure the operability of industrial facilities, the level of seismic performance to maintain operability may vary depending on the structural behavior characteristics of the industrial facility, and a seismic design method is needed to satisfy this. In this study, a ground storage tanks Nonlinear seismic behavior characteristics(R-μ-T) were analyzed through nonlinear response history analysis, and based on this, a new reliability-based, performance-based seismic design method was proposed.

The Strain of Transverse Steel and Concrete Shear Resistance Degradation after Yielding of Reinforced Concrete Circular Pier (철근콘크리트 원형 교각의 횡방향철근 변형률과 항복이후 콘크리트 전단저항 저감)

  • Ko, Seong Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.1
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    • pp.147-157
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    • 2018
  • The basis of capacity design has been explicitly or implicitly regulated in most bridge design specifications. It is to guarantee ductile failure of entire bridge system by preventing brittle failure of pier members and any other structural members until the columns provides fully enough plastic rotation capacity. Brittle shear is regarded as a mode of failure that should be avoided in reinforced concrete bridge pier design. To provide ductility behavior of column, the one of important factors is that flexural hinge of column must be detailed to ensure adequate and dependable shear strength and deformation capacity. Eight small scale circular reinforced concrete columns were tested under cyclic lateral load with 4.5 aspect ratio. The test variables are longitudinal steel ratio, transverse steel ratio, and axial load ratio. Eight flexurally dominated columns were tested. In all specimens, initial flexural-shear cracks occurred at 1.5% drift ratio. The multiple flexural-shear crack width and length gradually increased until the final stage. The angles of the major inclined cracks measured from the vertical column axis ranged between 42 and 48 degrees. In particular, this study focused on assessing transverse reinforcement contribution to the column shear strength. Transverse reinforcement contribution measured during test. Each three components of transverse reinforcement contribution, axial force contribution and concrete contribution were investigated and compared. It was assessed that the concrete stresses of all specimen were larger than stress limit of Korea Bridge Design Specifications.

Analysis of flow rate-SS discharges characteristics and causes during rainfall season in Daegi-cheon Watershed (대기천 유역에서의 강우기 유량-SS배출 특성 및 원인분석 연구)

  • Kim, Jonggun;Lee, Suin;Park, Byeongki;Won, Chulhee;Kum, Donghyuk;Choi, Joongdae
    • Journal of Wetlands Research
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    • v.21 no.1
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    • pp.9-15
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    • 2019
  • The Daegi-cheon watershed is located in the upper part of the Han River, which has the representative highland vegetable growing complexes. This watershed has a large impact on the water quality and aquatic ecosystem in the upstream of the Han River by discharging a large amount of turbid water during rainfall season. For proposing an efficient turbid water management and policy, the analysis of the characteristics of flow rate and SS and its causes needs to be carried out preferentially. In this study, the relationship between flow rate and SS concentration was analyzed in the Daegi-cheon watershed, and in turn the turbidity characteristics were analyzed. As a result of the study, in the normal flood flow condition, it was shown that SS concentration changed arbitrarily due to various environmental factors. On the other hand, the SS concentration was considerably high in the very high flow condition. Based on the field survey, this could be the reason why the effects of the steep valley and slope collapse according to the very high flow rate as well as the source in the agricultural fields were greatly contributed. Therefore, it is necessary to develop a structural best management practice that can stabilize the steep slope and reduce river bed loss along with the typical source managements plans.

A Development of Representative Condition Evaluation Standard for LNG Storage Tank Structures (LNG 저장탱크 구조물의 종합적 상태평가기준 개발)

  • Kim, Jung-Hoon;Jo, Young-Do
    • Journal of the Korean Institute of Gas
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    • v.22 no.6
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    • pp.44-51
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    • 2018
  • As the LNG storage tank is aged, if there is a crack in the outer wall concrete or corrosion of the reinforcing steel, there is a risk of a major accident such as collapse of the structure depending on the type and degree of damage. Since 2014, LNG storage tanks have undergone precise safety diagnosis and safety inspection has been carried out. The condition evaluation criteria for each component have been revised and applied in January 2016. The condition evaluation standard is to evaluate the status of storage tanks based on the appearance survey and material test results of LNG storage tanks and it is important for maintenance. In addition, the representative condition evaluation standard that shows the comprehensive state of each LNG storage tank is important in maintenance, but the related standard for LNG storage tank outer concrete is not available in Korea and abroad, and development of the condition evaluation standard is necessary. In this paper, we examined the structural characteristics of LNG storage tanks, analyzed the status of the condition evaluation criteria for each member, and developed a comprehensive status rating system by weighting the members. We used the AHP(Analytic Hierarchy Process) technique and developed a representative conditon evaluation criteria through surveys of professional organizations.

The Structual Restoration on Gyeongju-Style Piled Stone-Type Wooden Chamber Tombs (경주식 적석목곽묘의 구조복원 재고)

  • Gweon, Yong Dae
    • Korean Journal of Heritage: History & Science
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    • v.42 no.3
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    • pp.66-87
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    • 2009
  • The definition of the structure of wooden chamber tomb(piled stone-type) is as follows. It is a tomb with wooden chamber, and stones were piled on top of the wooden chamber, and then a wooden structure was placed on top of the piled stones, and more stones were piled on top of the wooden structure, and sealed with clay. Of course this definition can vary according to periods, the buried, etc. Gyeongju-style piled stone type wooden chamber tombs have some distinguished characteristics compared to general definition of piled stone type wooden chamber tombs. Outside the wooden chamber, either stone embankments or filled-in stones were layed out, and pilet-in stones are positioned right above the wooden chamber, and almost every class used this type, and finally, it is exclusively found in Gyeongju area. First generations of this Gyeongju-style piled stone type wooden chamber tombs appeared in first half of 5th century. These tombs inherited characteristics like ground plan, wooden chamber, double chamber(inner chamber and outer chamber), piled stones, burial of the living with the dead, piled stones, from precedent wooden chamber tombs. However these tombs have explicit new characteristics which are not found in the precedent wooden chamber tombs such as stone embankments, wooden pillars, piled stones(above ground level), soil tumuluses. stone embankments and wooden pillars are exclusively found on great piled stone type above-ground level wooden chamber tombs such as the Hwangnamdaechong(皇南大塚). Stone embankments, wooden pillars, piled stones(above ground level) are all elements of building process of soil tumuluses. stone embankments support outer wall of above-ground level wooden chambers and disperse the weight of tumuluses. Wooden pillars functioned as auxiliary supports with wooden structures to prevent the collapse of stone embankments. Piled stones are consists of stones of regular size, placed on the wooden structure. And after the piled stones were sealed with clay, tumulus was built with soil. Piled stones are unique characteristics which reflects the environment of Gyeongju area. Piled stone type wooden chamber tombs are located on the vast and plain river basin of Hyeongsan river(兄山江). Which makes vast source of sands and pebbles. Therefore, tumulus of these tombs contains large amount of sands and are prone to collapse if soil tumulus was built directly on the wooden structure. Consequently, to maintain external shape of the tumulus and to prevent collapse of inner structure, piled stones and clay-sealing was made. In this way, they can prevent total collapse of the tombs even if the tumulus was washed away. The soil tumulus is a characteristic which emerges when a nation or political entity reaches certain growing stage. It can be said that after birth of a nation, growing stage follows and social structure will change, and a newly emerged ruling class starts building new tombs, instead of precedent wooden chamber tombs. In this process, soil tumulus was built and the size and structure of the tombs differ according to the ruling class. Ground plan, stone embankments, number of the persons buried alive with the dead, quantity and quality of artifacts reflect social status of the ruling class. In conclusion, Gyeongju-style piled stone type wooden chamber tombs emerged with different characteristics from the precedent wooden chamber tombs when Shilla reached growing stage.

A Study on the External Form Characteristic Depicted on the Deconstructional Fashion (해체주의 패션에 보여진 외형적 양식의 특성에 관한 연구)

  • 김혜정
    • Archives of design research
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    • v.13 no.3
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    • pp.271-280
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    • 2000
  • This is the deconstruction of functionism and means the complex phenomenon of disharmony such as the reputation of purity, search for history, irony and so on. The perceptional system of post modernist and deconstructionist philosopy, that allow us to have the critical angle of view such as the deconstruction of the existing foundation and the absence of the meaning of the reasoncentered thinking of the west, is shown to be grafted into design, fashion and so forth. These elements are taking root as the style of the end of the 20th century. The deconstructional fashion revolting against the existing regime has been reconstructed and created a innovative aesthetic sense by going so far as to address the way that doffing is formed, the way to handle materials and physiological and psychological elements. The deconstructional fashion depicted on new interpretation of the body proportion with planeness and specificity while ignoring three-dimensionality , structuristic rationality

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Ultrastructural Studies of Germ Cell Developments and Atypical Cells Occurred During Spermatogenesis in the Acini, and the Cyclic Changes in the Epithelial Cells With the Developmental Phases of the Seminal Vesicle in Rapana venosa (Valencienes) (피뿔고둥 Rapana venosa (Valencienes) 정소소엽 내에서의 생식세포 발달과 정자형성과정 중 출현하는 비정형 세포들의 미세구조적 연구 및 저정낭의 발달단계에 따른 상피세포들의 주기적 변화)

  • Lee, Il Ho;Chung, Jae Seung
    • The Korean Journal of Malacology
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    • v.31 no.1
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    • pp.9-19
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    • 2015
  • Germ cell development and cyclic changes in the epithelial cells of the seminal vesicle of the male rapa whelk, Rapana venosa, were investigated by cytological and histological observations. The process of germ cell development can be classified into five stages: (1) spermatogonial, (2) primary spermatocyte, (3) secodary spermatocyte, (4) spermatid, and (5) spermatozoon. In particular, four atypical cells (Type IA, IB, IIA and IIB cells) occur among normal germ cells in the acini during spermatogenesis. Presumably, the atypical cells, which have lysosome-like vacuoles or lysosome-like bodies in the cells, are involved in breakdown and absorption themselves in the acini. However, atypical cells were not found in the epithelial cells of the inner layer of the seminal vesicle. A considerable amount of spermatozoa are transported from the testis towards the the seminal vesicles until late July. The main coupulation period is between June and July. The process of the cyclical changes of the seminal vesicles can be classified into three phases: (1) resting, (2) accumulating, and (3) spent. Yellow granular bodies are involved in resorption or digestion of residual spermatozoa.