• Steel and Composite Structures
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• 제35권3호
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• pp.353-370
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• 2020

This paper describes a new type of replaceable fuse for moment resisting frames. Column-tree connections with beam splice connections are frequently preferred in the moment resisting frames since they eliminate field welding and provide good quality. In the column-tree connections, a part of the beam is welded to the column in the shop and the rest of the beam is bolted with the splice connection in the field. In this study, a replaceable reduced beam section (R-RBS) connection is proposed in order to eliminate welding process and facilitate assembly at the site. In the proposed R-RBS connection, one end is connected by a beam splice connection to the beam and the other end is connected by a bolted end-plate connection to the column. More importantly is that the proposed R-RBS connection allows the replacement of the damaged R-RBS easily right after an earthquake. Pursuant to this goal, experimental and numerical studies have been undertaken to investigate the performance of the R-RBS connection. An experimental study on the RBS connection was used to substantiate the numerical model using ABAQUS, a commercially available finite element software. Additionally, five different finite element models were developed to conduct a parametric study. The results of the analysis were compared in terms of the moment and energy absorption capacities, PEEQ, rupture and tri-axiality indexes. The design process as well as the optimum dimensions of the R-RBS connections are presented. It was also demonstrated that the proposed R-RBS connection satisfies AISC criteria based on the nonlinear finite element analysis results.

• International Journal of Concrete Structures and Materials
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• 제8권2호
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• pp.99-116
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• 2014

The American Concrete Institute (ACI) 318-11 permits the use of the moment magnifier method for computing the design ultimate strength of slender reinforced concrete columns that are part of braced frames. This computed strength is influenced by the column effective length factor K, the equivalent uniform bending moment diagram factor $C_m$ and the effective flexural stiffness EI among other factors. For this study, 2,960 simple braced frames subjected to short-term loads were simulated to investigate the effect of using different methods of calculating the effective length factor K when computing the strength of columns in these frames. The theoretically computed column ultimate strengths were compared to the ultimate strengths of the same columns computed from the ACI moment magnifier method using different combinations of equations for K and EI. This study shows that for computing the column ultimate strength, the current practice of using the Jackson-Moreland Alignment Chart is the most accurate method for determining the effective length factor. The study also shows that for computing the column ultimate strength, the accuracy of the moment magnifier method can be further improved by replacing the current ACI equation for EI with a nonlinear equation for EI that includes variables affecting the column stiffness and proposed in an earlier investigation.

• International Journal of Concrete Structures and Materials
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• 제9권4호
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• pp.401-413
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• 2015

In this study the progressive collapse resisting capacity of a RC beam-column subassemblage with and without strengthening was investigated. Total of five specimens were tested; two unreinforced specimens, the one designed as gravity load-resisting system and the other as seismic load-resisting system, and three specimens reinforced with: (i) bonded strand, (ii) unbonded strand, and (iii) side steel plates with stud bolts. The two-span subassemblages were designed as part of an eight-story RC building. Monotonically increasing load was applied at the middle column of the specimens and the force-displacement relationships were plotted. It was observed that the gravity load-resisting specimen failed by fractures of re-bars in the beams. In the other specimens no failure was observed until the maximum displacement capacity of the actuator was reached. Highest strength was observed in the structure with unbonded strand. The test result of the specimen with side steel plates in beam-column joints showed that the force-displacement curve increased without fracture of re-bars. Based on the test results it was concluded that the progressive collapse resisting capacity of a RC frame could be significantly enhanced using unbonded strands or side plates with stud bolts.

• 한국환경농학회지
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• 제16권2호
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• pp.115-118
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• 1997

When the light metals such as $Ca^{++}$ and $Mg^{++}$ were added to heavy metal solution, the adsorption of heavy metals was increased by 20 to 30% more, but there were no differences between species. $Pb^{++}$ was the most adsorbed metal(99.5%), and the adsorption ratio of $Cd^{++}$ was significantly improved. In addition, when the light metal concentration was increased to 100ppm, the adsoption ratios of all four heavy metals were reached to 92 to 99%, while coniferous barks showed only 85 to 92%. On the mixture of four heavy metals, the adsorbed amount of each metal was significantly reduced, compared with that of one heavy metal, while $Zn^{++}$ showed the adsorption improvement to 95%. On the column experiment, $Pb^{++}$ was almost completely adsorbed in the upper part of column, and the adsorbed amount of $Cu^{++}$ was gradually decreased depending on column depth. However, $Cd^{++}$ and $Zn^{++}$ were not influenced by column height, and constantly adsorbed on various column height. Based on the above results, each heavy metal had different adsorption mechanism.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.349-356
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• 2010

In this study, a new design method of pile bent structure considering plastic hinge was proposed on the basis of the beam-column model. Based on the analysis results, it is found that the positioning of plastic hinge on the pile bent structure was influenced by nonlinear behavior of material and p-$\Delta$ effect. Moreover, concrete cracking began to occur at the joint section between the pile and column in case of pile bent structure with different cross-sections. The plastic hinge can be developed on the pile bent structure when large displacement was occurred, and pile bent structures can be maintained well only if it is developed on the column part. Therefore, in this study, the optimized cross-section ratio between column and pile was analyzed to induce the plastic hinge at the joint section between the pile and column. Based on this, the optimized diameter ratio of pile and column can be obtained below the inflection point of the bi-linear curve depending on the relations between column-pile diameter ratio($D_c/D_p$) and normalized lateral cracking load ratio($F/F_{Dc=Dp}$). And through this study, it is founded that in-depth limit($L_{As}$=0.4%) normalized by the pile length($L_P$) are proportionally decreased as the pile length($L_P/D_P$) increases up to $L_P/D_P$=17.5, and beyond that in-depth limit converges to a constant value. Finally, it is found that the proposed limit depth by taking into account the minimum concrete-steel ratio would be more economical design of the pile bent structure.

• 국제강구조저널
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• 제18권5호
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• pp.1761-1771
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• 2018

In this paper, a hysteretic model of rectangular hollow section (RHS) columns that includes the deteriorating range caused by local buckling is proposed. The proposed model consists of the skeleton curve, the Bauschinger part that appears before reaching the maximum strength, the strength increasing part of the deteriorating range, and the unloading part. Of these, the skeleton curve, including the deterioration range caused by local buckling, which is considered to be equivalent to the load-deformation relationship under monotonic loading, is obtained through an analytical method. Bi-linear hysteretic models based on experimental results are applied to the Bauschinger part and the strength increasing part. The elastic stiffness is applied to the unloading part. The proposed model is verified by comparing with experimental results of RHS columns under monotonic and cyclic loading.

• 대한수의학회지
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• 제33권4호
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• pp.597-603
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• 1993

The purpose of this stady was to investigate division cells by in vivo bromodeoxyuridine(Brdur) immunohistochemistry for labeling the proliferative epithelial cells in the gastrointestinal tracts of rats. Rats were administrated intraperitonially by twice consecutive injections of 24 hr interval with Brdur(0.05mg/g BW/time) and then were sacrificied at 1 hour after last injection. The specimens were taken from the stomach, small intestine(ileum), and large intestine(colon). The well-oriented crypts and villi in the preparations were examined, The crypt columns and villi were devided into 10 segments from crypt base to surface of the lumen or to villis top. Labeling index(LI) was measured by counting the number of Brdur-positive cells against the total number of crypt column cells in the stomach and large intestine and also against the total numbers of crypt column and it's villi epiterial cells in the small intestine. 1. In the stomach, the LI in each part from segment 1 to segment 10 of the crypt column were 4.2%, 5.0%. 6.6%, 9.0%, 11.3%, 15.3%, 9.3%, 15.6%, 11.3%, 0%, respectively and it's mean LI were 8.7%. The Brdur-positive epithelial cells were predominantly located in the middle regions and middle-upper regions of the crypt columns. 2. In the small intestine, the LI in each part from segment 1 to segment 10 of were 62.4%, 50.9%, 27.8%, 22.5%, 18.6%, 12.1%, 7.5%, 4.3%, 2.5%, 1.4%, respectively and it's mean LI were 21.0%. The Brdur-positive epithelial cells were predominantly located in the lower regions of the crypt columns and tended to be less in the higher regions of the villi than that in the crypt column. 3. In the large intestine, the LI in each part from segment 1 to segment 10 of the crypt column were 19.4%, 29.9%, 34.1%, 41.6%, 41.2%, 32.4%, 25.4%, 15.4%, 10.8%, 1.2%, respectively and it's mean LI were 25.1%, The Brdur-positive epithelial cells were predominantly in the middle and middle-lower regions of the crypt columns. 4. The organs with higher LI were ordered as the large intestine(25.1%), small intestine(21.0%) and stomach(8.7%).

• 한국지반공학회논문집
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• 제26권2호
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• pp.33-43
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• 2010

지열은 고효율 신재생에너지로 각광을 받고 있으며 건축물의 냉난방 설비 시스템으로 활용이 점차 확산되고 있다. 지열 히트펌프 중에서 지하수를 열원으로 사용하는 단일심정(Standing column well)은 특히 효율이 높고 초기설치비용이 저렴하며 국내 지반 수리조건에 적합하다. 반면, 국내에는 아직 SCW의 성능을 평가할 수 있는 수치해석 모델이 없으며 국내 자료를 적용한 수치해석이 수행된 바 없다. 본 연구에서는 SCW 수치해석 모델을 유한체적해석 프로그램을 이용하여 구축하였다. 수치적 모델은 수리 열 연계해석을 수행하여 열이류, 대류, 전도를 모두 모사한다. SCW 모델은 미국과 국내에서 계측된 현장 데이터를 통하여 검증하였다. 비교 결과 본 연구에서 구축된 수치해석 모델은 정확하게 SCW의 거동을 예측할 수 있는 것으로 나타났다. 검증된 수치해석 모델은 동반논문에서 매개변수연구에 활용되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.869-872
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• 2005

This research studied robust design of column part for LCD transfer system. $1^{st}$ DOE(Design of Experiment)was conducted to find out main effect factors. 36 experiments were performed and their results were shows that the geometric parameters(Low-length, Side-length, Upper-thickness, Middle-thickness)are more important than other factors. The main effect plots shows that the maximum deflection of column is minimized with increasing Low-length, Side-length, under-thickness and Middle-thickness. $2^{nd}$ DOE was conducted to obtain RMS(Response Surface Method)equation 25 experiments were conducted. The CCD(Central Composite Design)technique with four factors were used. The coefficient of determination $(R^2)$ for the calculated RSM equation was 0.986. Optimum design was conducted using the RSM equation Multi-island genetic algorithm was used to optimum design. Optimum value for Low-length. Side-length, Upper-thickness and Middle-thickness were 299.8mm, 180.3mm, 21.7mm, 21.9mm respectively. An approximate value of 5.054mm in deflection was expected to be a maximum under the optimum conditions. Six sigma robust design was conducted to find out guideline for control range of design parameter. To acquire six sigma level reliability, the standard deviation of design parameter should be controlled within 2% of average design value.

• Asian-Australasian Journal of Animal Sciences
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• 제16권2호
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• pp.165-171
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• 2003

Sixty semen ejaculates collected at weekly interval from four Murrah Buffalo bulls over a period of seven months (Nov.1999 to May 2000) were used in the present study. Three buffer medium (sodium citrate, TES and Tris) were used for soaking of sephadex. Three grades of sephadex (G-15,G-100, and G-200) were used for preparation of columns. Columns of three different height (one, two and three cm) were used for separation of semen. Twenty semen ejaculates were used in each project. In the first experiment each semen ejaculates was divided into four parts. One part was kept as control and other three parts were passed thought one cm column of sephadex G-15 prepared in three different buffers. There was significant (p<0.05) increase in percent progressive sperm motility and percent live spermatozoa and decrease in percent abnormal spermatozoa and percent spermatozoa with damaged acrosome as well as sperm numbers after filtration through all the three columns. Sperm quality obtained in the filtrate of column prepared in Tris buffer was better in comparison to other two buffers. So the Tris buffer was used in the second trial. Twenty semen ejaculates were used in this experiment. Each semen ejaculate was divided into four parts. One part was kept as control (non-filtered) and other three parts were passed through columns of different grade of sephadex (G-15, G-100 and G-200). Progressive sperm motility and live sperm percentage improved significantly while decline in percent abnormal spermatozoa and percent spermatozoa with damaged acrosome and sperm concentration was observed after filtration through all the columns as compared to control (non-filtered) semen. Since post filtration quality of semen was better in the sephadex G-100 column, therefore it was selected for the next experiment. In third experiment, Tris buffer and sephadex G-100 were used for preparing columns of different height (one, two and three cm) and twenty semen ejaculates were filtered. The quality characteristics of semen (percent progressive sperm motility, percent live spermatozoa and sperm concentration) after filtration through one cm column were significantly (p<0.05) higher than after filtration through columns of two and three cm height. However non -significant (p>0.05) difference due to height of columns was observed for percent abnormal and percent damaged acrosome but 1 cm column comparatively gave better result than of 2 and 3 cm column height.