In this study, we focus on the feasibility of structural topology optimization for a steel-timber composite beam design of optimally allocating glue-laminated timbers into a web with openings under the condition of given steel flanges. The motivation of this study is to topologically take maximal stiffness harmonizing both tension and compression performance of the steel-timber composite beam and become the eco-frandly timber design for buidling members. As a result of this study, the key web-openings allocation becomes triangle spaces, i.e., empty or no materials, of optimal topologies of both a pure timber plate and a steel flange-web timber plate without web-openings. Several applicable examples verify the effectiveness of topology optimization for steel-timber beams with web-openings.

Recently, machine learning is widely used to solve optimization problems in various engineering fields. In this study, machine learning is applied to development of a control algorithm for a smart control device for reduction of seismic responses. For this purpose, Deep Q-network (DQN) out of reinforcement learning algorithms was employed to develop control algorithm. A single degree of freedom (SDOF) structure with a smart tuned mass damper (TMD) was used as an example structure. A smart TMD system was composed of MR (magnetorheological) damper instead of passive damper. Reward design of reinforcement learning mainly affects the control performance of the smart TMD. Various hyperparameters were investigated to optimize the control performance of DQN-based control algorithm. Usually, decrease of the time step for numerical simulation is desirable to increase the accuracy of simulation results. However, the numerical simulation results presented that decrease of the time step for reward calculation might decrease the control performance of DQN-based control algorithm. Therefore, a proper time step for reward calculation should be selected in a DQN training process.

PURPOSES : This study evaluates the long-term performance of the asphalt overlay designed by the Seoul pavement design method which determines overlay thickness by considering existing pavement conditions, traffic volume, and bearing capacity of the pavement. METHODS : A total of 76 sections including 17 control sections and 59 design sections were constructed under various traffic conditions, overlay thicknesses and asphalt mixtures. The performance of the pavements has been monitored up to 60 months in terms of surface distresses, rutting, and longitudinal roughness. The service life of the pavements was estimated to be the period when the Seoul pavement condition index (SPI) becomes 6.0, i.e., a rehabilitation level. RESULTS : Overall, the service life of the pavements was 72 months in the control and 120 months for the design sections. For relatively thinner overlay sections than designed, the service life reduced significantly; 36 months for 15cm thick overlay and 120 months for 25cm thick overlay. The service life of the pavement in the bus-only lane was 78 months, which is 30 months shorter than that in mixed-traffic lanes. Out of the bus-only lanes, 56% of the pavement along bus stop was deteriorated early to be a poor condition while only 2% of the pavement in a driving lane was degraded to be poor. The overlay with Stone Mastic Asphalt (SMA) in the wearing surface had 38% longer life than that with conventional dense graded mixtures. CONCLUSIONS : Most of the overlays sections designed by the Seoul pavement design method were expected to survive 10 years, except for bus-only lanes. The control sections having 5 to 10 cm thick overlays showed significant lower performance than the design sections. Thus proper thickness and materials considering the characteristics of existing pavement and traffic volumes should be applied to secure the service life of overlays.

Recently, an unprecedented emerging infectious disease has rapidly spread, causing a global shortage of wards. Although various temporary beds have appeared, the supply of wards specializing in infectious diseases is required. Negative pressure isolation wards should maintain their function even after an earthquake. However, the current seismic design standards do not guarantee the negative pressure isolation wards’ operational (OP) performance level. For this reason, some are not included in the design target even though they are non-structural elements that require seismic design. Also, the details of non-structural elements are usually determined during the construction phase. It is often necessary to complete the stability review and reinforcement design for non-structural elements within a short period. Against this background, enhanced performance objectives were set to guarantee the OP non-structural performance level, and a computerized tool was developed to quickly perform the seismic design of non-structural elements in the negative pressure isolation wards. This study created a spreadsheet-based computer tool that reflects the components, installation spacing, and design procedures of non-structural elements. Seismic performance review and design of the example non-structural elements were conducted using the computerized tool. The strength of some components was not sufficient, and it was reinforced. As a result, the time and effort required for strength evaluation, displacement evaluation, and reinforcement design were reduced through computerized tools.

Seismic demand on nonstructural components (NSCs) is highly dependent on the coupled behavior of a combined supporting structure- NSC system. Because of the inherent complexities of the problem, many of the affecting factors are inevitably neglected or simplified based on engineering judgments in current seismic design codes. However, a systematic analysis of the key affecting factors should establish reasonable seismic design provisions for NSCs. In this study, an idealized 2-DOF model simulating the coupled structure-NSC system was constructed to analyze the parameters that affect the response of NSCs comprehensively. The analyses were conducted to evaluate the effects of structure-NSC mass ratio, structure, and NSC nonlinearities on the peak component acceleration. Also, the appropriateness of component ductility factor (R p) given by current codes was discussed based on the required ductility capacity of NSCs. It was observed that the responses of NSCs on the coupled system were significantly affected by the mass ratio, resulting in lower accelerations than the floor spectrum-based response, which neglected the interaction effects. Also, the component amplification factor (a p) in current provisions tended to underestimate the dynamic amplification of NSCs with a mass ratio of less than 15%. The nonlinearity of NSCs decreased the component responses. In some cases, the code-specified R p caused nonlinear deformation far beyond the ductility capacity of NSCs, and a practically unacceptable level of ductility was required for short-period NSCs to achieve the assigned amount of response reduction.

In this paper, considering the limits of existing smart pots, we introduce the research result of the new smart pot that can easily grow various pet plants. Through Arduino control kit which is the one of the open source computing platform, electric circuit and equipment to fulfil the functions of the smart pot is newly designed and made. Especially the head of pump which is main function in smart pot and the structure of electric equipment is theoretically calculated and Finite Element Analysis (FEA) tool is used for static analysis to prevent damage to the pots. After that, new smart pot is made with the researched design materials and perform the various functional investigations to grow the indoor plants.

In this study, magnetic characteristics of two models of permanent magnet actuator applied and used in the Recloser were studied, and the new model design was verified using numerical analysis on the operation and current characteristics of the magnet actuator accordingly. Such as the Recloser require fast operation characteristics to open the fault current, so when the moving and fixed contacts of a magnet actuator with permanent magnets that generate holding force come into contact, a high holding force is required, and when it open to circuit, the magnetic force is rapidly reduced. It demands very high performance. Therefore, the speed characteristics and current characteristics of the contact points of the magnet actuator for which the design was completed were compared.

In this study, stiffness evaluation was conducted on the main member, front cross member, and rear cross member, which are three components of sub-frame for SUVs (sports utility vehicles), through mode analysis. As for the design variables used in the analysis, the maximum frequency was examined by varying the width and height of each of the three parts into four types. Of course, the weight at this time is minimized, and the mode is set as a constraint that only bending occurs and no distortion occurs. As a result of the analysis, the member affecting the 1st mode was the rear cross member, and the member having the greatest influence on the 2nd mode was the front cross member. In addition, the member with the greatest influence on the 3rd mode appeared as the rear cross member, indicating that this part had the greatest effect on the bending stiffness.

우리나라에 등록 된 선박은 2019년 기준 전체 97,623척이다. 그 중 어선이 차지하는 비율은 약 67 %로 65,835척이 등록되어 있 다. 어선의 비율만큼이나 해양사고의 빈도수도 높다. 2020년 기준 전체 사고 3,535건 중 2,331건이 어선에서 발생했다. 즉 국내어선의 안전 성 향상을 위한 여러 제도적 마련이 필요한 실정이다. 본 연구에서는 어선의 안전향상을 위한 다양한 부분 중에서 어선과 관련된 국내외 조종성능에 대한 국내외 평가 규정을 살펴보았다. 또한 상선에 비하여 설계 기준이 명확히 정립되지 않은 어선의 타면적 설계 현황을 살 펴보기 위하여 국내 조업 중인 153척의 어선 타면적 비율를 조사하였다. 그 결과 대다수의 어선이 국제적 기준에 미달하여 타면적을 설계 하고 있음을 통계적으로 확인하였다. 향후 이러한 분석 결과는 국내 어선의 조종성능 향상을 위한 타면적 설계 기준마련을 위한 기초 자 료로 활용하고자 한다.

최근에는 경량화 문제에 대한 합리적인 솔루션을 제공하고 유용한 개념설계를 제공할 수 있는 다중 재료 구조 위상최적화가 더욱 중요해지고 있다. 기존의 MMTO(Multi-Material Topology Optimization)의 경우 후보 물질의 수가 증가할수록 설계변수의 수도 증가 하고, 결과적으로 계산 시간이 크게 증가한다. 따라서 PSM(Phase Section Method)과 같은 단일 설계변수를 갖는 MMTO가 제안되었 다. 본 연구는 조성비가 면적이나 부피비를 나타내지 못하고, 설계변수가 목표치에 충분히 집중되지 않고, 특정 재료가 요구량보다 적 게 생성되는 PSM의 세 가지 주요 제한점을 고려하여 이를 개선하는데 중점을 둔다. 이러한 한계를 극복하기 위해 재정의된 조성비와 더 나은 수렴을 위한 조정된 매개변수를 제안한다. 제안된 수정 사항의 유효성을 2차원 및 3차원 수치 예제를 통해 검증한다.

본 연구는 보험설계사의 코칭역량과 일터환경특성이 조직성과에 미치는 영향 을 규명하고, 대인관계의 매개효과를 실증적으로 규명하는 데 있다. 본 연구는 보험설계사를 대상으로 총 521부의 구글 설문을 수집하였고, SPSS와 AMOS를 사용하여 분석한 결과는 다음과 같다. 첫째, 보험설계사의 코칭역량과 조직성과 간의 상관관계를 살펴보면, 통계적 으로 유의미한 정적 상관관계가 있으며, 이는 보험설계사의 코칭역량이 높으면 조직성과도 높아짐을 의미한다. 둘째, 보험설계사의 대인관계와 조직성과, 코칭 역량과 대인관계, 일터환경특성과 대인관계 간의 상관관계를 살펴보면, 대부분 의 측정 변인들 간에 통계적으로 유의미한 정적 상관이 있는 것으로 나타났다. 셋째, 보험설계사의 코칭역량과 일터환경특성은 조직성과에 직접적으로 긍정적 인 영향을 미치고, 대인관계의 매개를 통해서도 조직성과에 영향을 미치는 것으 로 예측되어, 대인관계는 코칭역량과 조직성과, 일터환경특성과 조직성과의 관 계를 부분 매개하고 있음을 알 수 있었다. 이 연구를 통해서 보험설계사가 상담 시 사용하는 상담스킬이 코칭에서 사용 되는 코칭역량과 대단히 유사함을 규명하는 연구들이 더 진행되기를 제안한다.