• Journal of Korean Society of Steel Construction
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• v.29 no.6
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• pp.423-434
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• 2017

In this paper a systematic numerical analysis is performed to obtain the hysteresis behavior of partially restrained top and seat angle connections subjected to cyclic loading. This connection includes superelastic shape memory alloy (SMA) angles and rods in order to secure the recentering capacities as well as proper energy dissipation effects of a CFT composite frame. The three-dimensional nonlinear finite element models are constructed to investigate the rotational stiffness, bending moment capacity and failure modes. A wide scope of additional structural behaviors explain the different influences of the connection's parameters, such as the various thickness of connection angles and the gage distance of steel and SMA rods.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.174-175
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• 2003

현재 유통되고 있는 일반백미의 경우 소비자가 밥을 짓기 위해서는 쌀을 씻어야하는 번거로움 뿐만아니라 쌀 중량의 약 15배의 물이 소요되고, 또한 이때 발생된 쌀뜨물이 수질오염의 원인이 되기 때문에 무세미가공 및 보급 필요성이 점차 높아지고 있다. 무세미 가공분야의 선진국인 일본의 경우 ‘92년부터 습식 무세미조제기가 실용화되기 시작, 현재 사다께 등 6개사에서 기계장치를 생산보급 하고 있으며, 무세미의 유통도 일반화되어가고 있는 추세이다. 국내의 경우 무세미조제기는 근래에서야 습식 무세미 조제설비가 국산화되어 보급초기 단계 있으며, 무세미의 안정적 가공 및 보급을 위해서는 앞으로 많은 연구가 이루어져야 할 것으로 생각된다. 특히 습식의 경우 쌀이 물에 접촉하는 시간이 길 경우 품질저하의 우려가 크고, 쌀중량의 1.4배에 해당하는 물이 가공과정에 필요하기 때문에 물사용량을 억제할수 있는 가공기술의 개발 필요성이 커지고 있다. 따라서 본 연구에서는 물사용량을 최소화 할 수 있는 무세미 조제시스템을 개발하고자 하였으며, 주요결과를 요약하면 다음과 같다. 시작기는 연마 및 공기세척부, 정전기 세척부, 미세가수세척부로 구성하여 쌀이 단계적으로 세척될 수 있도록 제작되었다. 성능시험 결과, 각 세척공정별 세척수의 탁도 감소효과는 연마 및 공기크리닝부에서 22.67ppm, 정전기 크리닝부에서 8.33ppm, 미세가수세척부에서 17.34 ppm이 감소되는 것으로 나타났다. 특히 정전기세척부의 탁도감소 효과는 다른 두공정에 비해 작지만 제거가 쉽지 않은 미세한 쌀겨들을 제거하여 탁도를 개선을 시켰기 때문에 미세가수세척장치에서 가수량을 적게 사용하는데 기여한 것으로 판단된다. 가공시 적정 탁도를 확보할 수 있는 가수량은 430cc/kg로 기존의 습식에 비해 약 69%정도 세척수 절감효과가 있었다. 이때 미세가수세척부의 원통스크린 회전수는 108, 205rpm범위가 적정한 것으로 나타났다. 쌀의 품위는 탁도가 가공전 97.33ppm(일반백미)에서 가공후 최대 48.00ppm으로 낮아졌으며, 백도도 가공전 36.80에서 42.80으로 향상되어 씻지 않고도 밥을 지을수 있는 무세미 가공이 가능하였다. 이밖에 쇄립률은 가공전 5.30%에서 7.37%로 다소 증가하는 것으로 나타났고, 함수율은 가공전 15.60%에서 15.80%로 약 0.2%가 증가하였으나 기존의 연구결과에 비춰볼 때 문제가 되지 않을 것으로 여겨진다.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.149-158
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• 2006

The reduced beam section (RBS) steel moment connection has performed well in past numerous tests. However there still remain several design issues that should be further examined. One such issue on RBS connection performance is the panel zone strength. Although a significant amount of test data are available, a specific recommendation for a desirable range of panel zone strength versus beam strength has yet to be proposed. In this paper, the effects of panel zone strength on the cyclic performance of RBS connection are investigated based on the available test database from comprehensive independent testing programs. A criterion for a balanced panel zone strength that assures sufficient plastic rotation capacity while reducing the amount of beam buckling is proposed. Numerical studies to supplement the test results are then presented based on the validated finite element analysis. Satisfactory numerical simulation achieved in this study also indicates that numerical analysis based on quality finite element modeling can supplement or replace, at least in part, the costly full-scale cyclic testing of steel moment connections.

• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.169-177
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• 2011

This paper presents the results of the systematic finite element analysis of the in-plane bending moment of T-joints subjected to cyclic loadings. T-joints were fabricated using high-strength, circular, hollow sections. Three-dimensional, nonlinear finite element models of the welded T-joints were constructed to investigate the strength, rotational-stiffness characteristics, and failure modes. A wide scope of structural behaviors explain the influence of the joint geometric parameters, such as the chord and brace wall slenderness ratios and the ratio of the brace to the chord diameter, as well as the yield strength ratios and compressive-chord-stress effects on the ultimate in-plane bending moment capacity of the T-joint.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.3
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• pp.191-200
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• 2011

Levee failure cause the huge amount of damage to human and property. Overflow and erosion of levee are primary cause of a break in a levee but the analysis of breach pattern and impact is partially inadequate. The flow characteristics of meandering rivers are very important in field of river hydraulics that should be studied in practical viewpoints relating to river levee. In meandering the secondary flow that rotary direction is changed reciprocally occurs in three dimension is known. In this study flow characteristics of local river are considered and of meandering channels are analyzed using CCHE2D and FLOW3D. The stability and accuracy of models are examined comparing the measuring and analyzed data for the experimental channel and natural river(Namgang). Consequently, the flow characteristics in a meandering river are suggested precisely and it is essential that river levees having meandering river should be analyzed.

• Journal of Korean Society of Steel Construction
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• v.28 no.6
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• pp.439-448
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• 2016

Extended end-plate connections(EEPC) are a type of connection applied in Pre-Engineered Building structures comprising beam-column connections of steel structures or tapered members. Extended end-plate connections(EEPC) show different behavioral characteristics owing to the influence of plate thickness, gauge distance of high strength bolt, diameter of high strength bolt frame, and the number of high strength bolts. In the USA and Europe, extended end-plate connections(EEPC) are applied in beam-column connections of steel structures in various forms; however, these are not widely applied in structures in Korea.This can be attributed to the fact that the proposal of design strength types for extended end-plate connections(EEPC), proposal of connection specifications, evaluation of seismic performance, and are not being performed appropriately. Therefore, the purpose of this study is to provide basic data for the domestic application of Unstiffened extended endplate connections. To realize this, nonlinear finite element analysis was conducted on a 12-mm thick Unstiffened extended endplate connections.

• Journal of Korean Society of Steel Construction
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• v.22 no.3
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• pp.281-291
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• 2010

In this study, a five-story steel frame was designed in accordance with KBC2005 to evaluate the effects of the beam-column connection on the structural behavior. The connections were designed as fully rigid and semi-rigid. The fiber model was used to describe the moment-curvature relationship of the steel beam and the column, the power model for the moment-rotation angle of the semi-rigid connection and the three-parameter model for the hysteretic behavior of the steel beam, column, and connection. The structure was idealized as separate 2-D frames and as connected 2-D frames. The peak ground accelerations of four earthquake records were modified in a time-history analysis for the levels of the mean return period and for the maximum base-shear force in a pushover analysis. The top story displacement, base-shear force, story drift, demanded ductility ratio for the semi-rigid connection, maximum bending moment of the column, beam, and connection, and distribution of the plastic hinge were examined in the time-history analysis. The frame with the semi-rigid connection yielded a lower base-shear force, less magnitude, and increasing ratio in the bending moment of the column, beam, and connection than the frame with a fully rigid connection. The TSD connection was deemed to have secured the economy and safety of the sample structure that was subjected to seismic excitation for the Korean design level.

• Journal of the Korean Orthopaedic Association
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• v.56 no.6
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• pp.498-503
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• 2021

Purpose: The aim of this study were to find ideal entry point of straight antegrade humeral intramedullary nail (SAHN) for the treatment of proximal humerus fracture in Korean and to analyze anatomical conformity using computed tomography. Materials and Methods: From May 2014 to October 2016, the study was conducted retrospectively on 74 Korean patients who had taken computed tomography on both normal and affected shoulder joint as result of shoulder injury. The mean age of the patients was 64.5 years (range, 22-95 years). Radiologic evaluation was done using multiplanar reconstruction technique of the computer tomography on normal proximal humerus. We located ideal entry point of SAHN as the point where humerus intramedullary center axis and humeral head meet. Distance between the entry point and local anatomical landmark was measured. We defined the critical distance as the distance between entry point and the most medial point of the supraspinatus attachment site. For adequate fixation and avoidance of injury to rotator cuff, critical distance should be over 8 mm according to Euler, and we defined the critical type when it is less than 8 mm. Critical distance, sex, age, height, body weight, body mass index was evaluated for the statistical significance. Results: The ideal entry point was as follows: the mean anteroposterior distance, the sagittal distance to the lateral margin of bicipital groove, was 11.5 mm and the mean mediolateral distance, the coronal distance to the lateral margin of grater tuberosity, was 20.5 mm. The mean critical distance, distance from the entry point to the just medial to insertion of the supraspinatus tendon, was 8.0 mm. Critical type with critical distance less than 8 mm was found in 41 in 74 patients (55.4%). Conclusion: The ideal entry point of SAHN in Korean was located on 11.5 mm posteriorly from the lateral margin of bicipital groove and 20.5 mm medially from lateral margin of greater tuberosity. More than half of the cases were critical type. Since critical type can possibly cause rotate cuff injury during nail insertion on entry point, surgeon should consider anatomical variance before choosing surgical option.

• Journal of Korean Society of Steel Construction
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• v.29 no.1
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• pp.81-88
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• 2017

Residual stress is defined as stress that already exists on a structural member from the effects of welding and plastic deformation before the application of loading. Due to such residual stress, welded H-section compression members under centroidal compression load can undergo buckling and failure for strength values smaller than the predicted buckling load and specified compressive strength. Therefore, this study was carried out to evaluate the effect of residual stress from welding on the determination of the buckling load and specified compressive strength of the H-section compression member according to the column length variation. A three-dimensional nonlinear finite element analysis was performed for the H-section compression member where the welded joint was fillet welded by applying heat inputs of 3.1kJ/mm and 3.6kJ/mm using the SAW welding method.

• Journal of Bio-Environment Control
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• v.29 no.4
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• pp.473-479
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• 2020

In this study, the structural experiment was conducted with two types of specimens to investigate the mechanical behavior of the column-rafter-purlin connection of an arch-type greenhouse under monotonic loading. Based on the experimental results, the flexural performance was analyzed for two types of connections, and connection classification was attempted. Type B showed 77% of flexural performance compared to Type A, and both types showed that the rigidity and flexural strength did not reach the level of the full rigid. The behavior of the column-rafter-purlin connection was dominated by local buckling due to deformation of the weld and fasteners. As a result of connection classification by AISC standard, both Type A and B connections showed a result that did not meet the rigid connection performance assumed during design, and were classified as simple connection. Therefore, the connection performance evaluation and classification results show that the greenhouse design should be made in consideration of connection performance and in order to design a reliable greenhouse structure, a study on establishing clear design standards for the greenhouse connection is necessary.