• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.1
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• pp.109-116
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• 2023

The purpose of this study was to investigate the influence of gender and load carriage difference on the lower extremity kinetics during stair descent. Ten healthy males and 10 healthy females were recruited (n=20). In the Maximum resultant velocity, it showed more velocity was decreased with difference by the change of gender (males>females) and load carriage (30%, 20%, 10%> 10%). And, resultant velocity showed interaction between gender and a load (load>gender). Main effect by gender during stair descent showed leg length was decreased in females than that of males at initial contact phase. Also, main effect by gender during stair descent showed more hip, knee flexed and plantar flexion of ankle joint in females than that of males. In the kinetics variables, main effect by gender during stair descent showed more higher reaction force of medial-lateral direction, and leg stiffness in males than that of females. We found that females successfully accommodated a load during stair descent by decreasing the range of motion of the hip joint angle and resultant velocity of movement. Males, on the other hand, require greater medial-lateral, vertical reaction force, and leg stiffness to accommodate a load, and control of momentum.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.467-475
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• 2009

Existing studies have suggested Universal Curve only for supplemental damping by damper. Therefore net damping has been determined by means of arithmetic summation between intrinsic, aero-damping of cable and supplemental damping of damper. However linear combination approach by means of the arithmetic summation is not enough theoretical background. So validity of this approach should be verified in order to design adequate cable-damper system by engineers. This study establishes governing differential equation which can consider intrinsic, aero-damping and supplemental damping as well. And also analysis method is solved by combination of muller method and successive iteration method. Consequently, this study succeeds in verification for validity of linear combination approach. As a result of this study, linear combination approach is limitedly effective in case of low stiffness and optimum damping coefficient of damper, short distance from support to damper, lower vibration mode, low aero-damping, and normal windy environment. Whereas this study will be effective in case of opposite conditions, and existing studies or linear combination approach occur to further error. Meaning of this study presents exact solution for net damping of cable-damper system, and verifies linear combination approach by means of the analysis method. In the future, if monitoring of optimum damping coefficient of a damper against aero-damping is feasible on time, algorithm of this study will be available for control of cable and semi-active damper system such as magneto-rheological damper.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.39-45
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• 2024

Seismic safety of expansion joints for piping systems has been underscored by water pipe ruptures and leaks resulting from the Gyeongju and Pohang earthquakes. Metal bellows in piping systems are applied to prevent damage from earthquakes and road subsidence in soft ground. Designed with a series of corrugated segments called convolutions, metal bellows exhibit flexibility to accommodate displacements. Several studies have examined variations in convolution shapes and layers based on the intended performance to be evaluated. Nonetheless, the research on the seismic performance of complex bellows having multiple corrugation heights is limited. In this study, monotonic loading tests, cyclic loading tests, and fatigue tests were conducted to evaluate the shear performance in seismic conditions, of metal bellows with variable convolution heights. Single- and triple-layer bellows were considered for the experimentation. The results reveal that triple-layer bellows exhibit larger maximum deformation and fatigue life than single-layer bellows. However, the high stiffness of triple-layer bellows in resisting internal pressure poses certain disadvantages. The convolutions are less flexible at lower displacements and experience leakage at a rate related to the variable height of the convolutions in certain conditions. At lower deformation rates, the fatigue life is rated higher as the number of layers increase. It converges to a similar fatigue life at higher deformation rates.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.2 s.72
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• pp.203-212
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• 2006

Although composite construction has many mechanical advantages over noncomposite construction, the design of noncomposite construction for skew bridges with large skew angels has been often checked because composite construction caused large stresses in the bridge deck. But there is somewhat difficulty to apply noncomposite construction in the field because of the structural problem such as the slip at the interface between the concrete deck and steel girders. In this study, the validity of the application of the composite construction to skew angles with large skew angles is investigated by analyzing effects of two interactions such as composite and noncomposite actions between the concrete deck and steel girders on the behavior of skew bridges. A series of parametric studies for the total 27 simply supported skew bridges was conducted with respect to parameters such as girder spacing, skew angle, and deck aspect ratio. The improvement of the behavior of composite skew bridges was examined by using the concept of the stiffness adjustment of bearings which I suggested in previous research. Results of analyses show that a more desirable behavior of skew bridges can be obtained from composite construction instead of noncomposite construction and the method of the stiffness adjustment of bearings results in a more rational and economical design of composite skew bridges and substructures.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.261-273
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• 2011

Recently, the demands for steel frame are increasing because of the trend and due to the demand for bigger and higher buildings. In the analysis of typical steel frame, connections are based on the idealized fixed or pinned connection. A fixed connection assumes that the relative angle of each member before deformation is the same after the transformation. Therefore, the stiffener reinforces the connection to sufficient rigidity and stability of the panel zone. In the economical aspect, however, the necessity of connection that the stiffener reinforcement has omitted is increasing due to the excessive production as well as labor costs of connection. In contrast, pinned connection is assumed that bending moments between the beams and columns do not transfer to each member. This is easy to make in the plant and the construction is simple. However, the structural efficiency is reduced in pinned connection because connection cannot transfer moments. The introduction of this semirigid process can decide efficient cross-sectional dimensions that promote ease in the course of structural erection, as performed by members in the field-a call for safety in the entire frame. Therefore, foreign countries exert efforts to study the practical behavior and the results are applied to criterion. This paper analyzes the semirigid connection of domestic steel by design specifications of AISC/LRFD and make data bank that pertain to each steel. After wards, the results are compared to those of idealized connection; at the same time, this paper presents a design method that matches economic efficiency, end-fixity, and rotational stiffness.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.559-566
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• 2012

In this study, fiber elements and a spring are used to build a reinforced concrete shear wall model. The fiber elements and the spring reflect flexural and shear behaviors of the shear wall, respectively. The fiber elements are built by inputting section data and material properties. The spring parameters representing strength and stiffness degradation, pinching, and slip were determined by comparing behaviors of fiber element and VecTor2 results. 'Pinching4' model in OpenSees is used for shear spring. The parameter selecting process for shear spring is a complicated and time consuming process. To study the applicability of the fiber element, reinforced concrete buildings containing a shear wall are evaluated using nonlinear dynamic analysis with various wall aspect ratio (H/L), various beam heights, and stiffness and flexural strength of beam and wall ratios. The aspect ratio of the wall showed distinct difference in IDR (interstory drift ratio) of the models with and without spring. On the other hand, the height of beam and ratio of stiffness and flexural strength of beam and wall did not show clear relation.

• The Journal of Engineering Geology
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• v.32 no.3
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• pp.351-361
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• 2022

Numerical analysis performed to predict the behavior of Ipseok-dae columnar joints in Mudeungsan National Park to understand their stability and movement. The numerical analysis technique, 3DEC, is based on the discrete element method that can analysis discontinuities. The analysis used data for material properties derived from laboratory tests, which found that average density was 2.68 kN/m³, average normal stiffness was 3.15 GPa/m, average shear stiffness was 1.00 GPa/m, average cohesion was 0.51 MPa, and the average friction angle was 33°. The Ipseok-dae columnar joints were modeled on the basis of the field survey data for 15 joints located between the observation platform and the hiking trail. The numerical analysis assessed the behavior of each columnar joint by interpreting the displacement of the edges of its upper and lower surfaces. The greatest maximum displacement was found in columnar joint No. 6, and the greatest minimum displacement was found in joint No. 11. Analyzing the movements of five discontinuities in joint No. 11 indicated that the maximum displacement occurred at the 2nd level. The other levels were ordered 5th, 4th, 1st, and 3rd in terms of subsequent greatest displacements. Considering the total displacement in the 15 studied joints, the Ipseok-dae columnar joints are judged to be stable. However, considering the cultural and historical value of Mudeungsan National Park, it is regarded that the currents slope stability should be maintained by monitoring the individual rock blocks of the joints.

• Proceedings of The KACE
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• 2017.08a
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• pp.217-220
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• 2017

테크놀로지의 발전에 따라 교육에서도 테크놀로지를 도입하기 위한 움직임이 활발하게 진행되었다. 교육에서는 테크놀로지를 학생들이 학습 과정에서 겪는 문제점을 해결하기 위한 목적으로 활용하였다. 하지만, 교사들의 테크놀로지에 대한 전문성 부족으로 인하여, 교사들은 수업에 테크놀로지를 도입하는데 많은 어려움을 겪고 있었다. 테크놀로지를 기반으로 한 교사의 수업 전문성 발달을 위하여 테크놀로지 교수 내용 지식(TPACK)이 도입되었고, 교사의 TPACK 향상을 위한 연구가 많이 진행되었다. 최근에는 테크놀로지가 가진 한계점을 극복하기 위하여 새로운 테크놀로지 도구로써 프로그래밍이 주목받고 있다. 따라서 선행 연구에서는 프로그래밍을 기반으로 TPACK 교육 프로그램을 향상시키기 위한 교육 프로그램이 개발되었다. 본 연구에서는 김성원과 이영준(2017)에서 개발한 TPACK 교육 프로그램의 효과를 검색하기 위한 연구를 진행하였다. 교사에게 적합한 40차시의 TPACK-P 교육 프로그램을 개발하였고, 연구를 위하여 모집한 17명의 교사를 대상으로 교육 프로그램을 적용하였다. 또한, 교사의 TPACK 변화를 관찰하기 위하여 박기철과 강성주(2014)의 연구에서 개발한 검사 도구를 교육 프로그램 투입 전, 후에 실시하였다. 적용 결과, TPACK-P 교육프로그램을 통하여 교사의 TPACK은 통계적으로 유의미한 향상이 나타났다. 세부 영역에서는 Pedagogical Knowledge(PK), Technological Knowledge(TK), Technological Content Knowledge(TCK), Technological Pedagogical Knowledge(TPK), Technological Pedagogical Content Knowledge(TPACK)에서 통계적으로 유의미한 차이가 나타났다. 하지만, Content Knowledge(CK)와 Pedagogical Content Knowledge(PCK)에서는 통계적으로 유의미한 차이가 나타나지 않았다. 이러한 결과를 통하여 TPACK-P 교육 프로그램이 모든 영역은 아니지만, 테크놀로지와 관련된 지식과 교사의 TPACK 발달에 효과적인 것을 확인할 수 있었다. 본 연구에서는 TPACK-P 교육 프로그램을 통한 교사의 TPACK 변화를 검사 도구를 통하여 측정하였다. 후속 연구에서는 TPACK-P 교육 프로그램에 참여한 교사의 수업 전문성의 변화와 학교 현장에서 수업의 변화, 이에 대한 학생들의 반응을 측정하는 연구가 필요하다.

• Journal of Embryo Transfer
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• v.19 no.2
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• pp.147-153
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• 2004

본 실험에서는 수술적 방법을 이용하여 난관 절제술을 실시한 성숙 난자의 회수율과 카데터를 이용한 난자 회수율 그리고 새롭게 고안된 개 난자 회수용 니들을 이용한 회수율을 비교하였으며, 각각의 회수 방법이 성숙난자의 외형에 미치는 영향을 조사한 결과는 12두에서 난관절제술로 채취한 성숙난자의 회수율은 89.7% 이었다. 수술적 회수방법에서는 본 연구실에서 개발한 난자 회수용 니들을 난관내에 삽입-결찰한 후 난관-자궁 접합부에서 난자 회수용 배지를 관류하는 방법으로 평균 83.0%의 회수율을 얻었다. 이 같은 결과는 TomCat 카테터를 이용한 회수율 (68.9%)과 난자 회수용 니들을 결찰하지 않고 관류한 방법 (73.5%) 보다 유의적으로 높은 회수율을 나타내었다 (p<0.05). 또한 난관 절제술과 각각의 수술적 방법으로 회수한 난자의 형태학적 차이는 관찰할 수 없었으나 난관 절제술과 난자회수용 니들을 결찰하여 회수한 난자의 형태와 난질이 Tom Cat 카테터나 결찰하지 않은 니들을 이용하였을 때보다 영향을 덜 받는 경향을 나타내었다 (각각 72.0%, 73.8%와 62.8%, 69.6%).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.77-80
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• 2011

Medical robot has four fields. Surgery assistant robot, robotic surgery, Surgery Simulator, rehabilitation robot. Thus, medical robots is often high precision and reliability requirements for operations are being developed. Medical service robot's another sector is care for service robots. Care services robot is the hospital's reception work and biometric data acquisition of patients, the hospital in location and content information provide to patients. But now medical service robot practical acceptance process failed to progress. In this paper were the medical service robot systems design and implementation. Implemented the robot system is using the standard protocols for the exchange of medical information and can be linked with hospital information system. The hospital's patient reception and processing, to provide care waiting number information.