The sub-frame is located on the lower body of a monocoque type vehicle and serves as an engine and suspension, and is an important object part that receives a lot of load. The existing press-type sub-frame has a large number of parts for assembling, which causes an increase in cost. Changing the machining form of this part from the existing press-type machining method to the hydro-forming machining method has the advantage of reducing the cost and weight at the same time due to the reduction of the process. Therefore, in this study, the purpose of this study is to change the design so that the sub-frame of the existing press type can be changed to the hydro-forming process method. To this end, we intend to present a design method by analyzing the effect on the rigidity of the sub-frame using the existing machining method through shape optimization analysis.

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.

목적 : 본 연구는 한국과 중국 성인 남녀의 안면 크기와 동공 간 거리를 조사하고, 현재 착용하고 있는 안경테의 크기 및 디자인 형상에 대해 비교를 하고자 하였다. 방법 : 경북 경산에 위치한 안경원을 방문한 20~30대 성인 남녀 각각 100명, 중국 지린성에 위치한 안경원을 방문한 20~30대 성인 남녀 각각 100명, 총 400명에 자료를 전향적 방법으로 수집하였다. 대상자들의 안면 크기 는 모바일 애플리케이션(Eye measure 1.21, Dotty Digital 2018, USA)을 이용하여 측정하였으며, 동공 간 거 리는 수동식 동공 간 거리계(PD-5, TOPCON, Japan)를 이용하여 원용과 근용 각각의 동공간 거리를 측정하였 다. 착용하고 있는 안경테에 대한 크기는 boxing system에 준하여 측정하였고, 안경테의 종류는 모양(원형, 타원 형, 직사각형), 림의 형태(온테, 반무테, 무테), 재질(플라스틱, 금속, 콤비)로 구분하여 분류하였다. 결과 : 안면 크기 측정범위는 149.73±6.28 mm(중국 여성)~152.29±14.71 mm(한국 남성)이었으나, 그룹 간 통계적 유의성은 없었다(p=0.147). 원용 및 근용 동공 간 거리 측정에서는 모두 그룹 간 통계적 유의성이 있었 다(p<0.001). 안경테의 크기 측정인 렌즈 삽입부의 크기(eye size), 연결부의 길이(bridge size) 그리고 수직 길이 (vertical height)에서 모두 그룹 간 통계적 유의성이 있었다(p<0.001). 한국과 중국의 남녀 대상자들의 착용 중 인 안경테에서 콤비 재질을 제외하고(p=0.790), 모든 항목에서 통계적 유의성이 있었다. 결론 : 본 연구는 한국과 중국 성인 남녀 간의 안면 크기는 차이는 없었지만, 동공 간 거리는 차이가 있었다. 착용 중인 안경테의 크기는 한국과 중국 착용자 간의 차이가 뚜렷하게 나타났으며, 한국 성인은 상대적으로 원형 테를 많이 착용하고 있지만, 중국은 직사각형의 안경테를 더 많이 착용하고 있었다. 따라서 나라 간 선호도가 다 름을 이해하고, 기호에 맞는 제품을 추천할 수 있어야 하고, 수출을 위한 안경 디자인을 할 때 안면의 형상 및 현 지인의 기호를 고려해야 할 것이다.

본 연구에서는 20,000 톤급 해양플랜트 상부구조물(Topside)의 플로트오버 설치작업을 위해 개발된 수동형 갑판 지지 프레임 (Deck support frame)의 구조설계에 대해 다양한 실험계획법을 이용한 최소중량설계와 민감도 평가의 비교연구를 수행하였다. 수동형 갑판 지지 프레임의 주요 구조부재의 두께 치수 변수는 설계인자로 고려하였고, 응답치는 중량과 강도성능으로 선정하였다. 최소중량설계와 민감도 평가의 비교연구에 사용한 실험계획법은 직교배열설계법, Box-Behnken 설계법, 그리고 Latin hypercube 설계법이다. 실험계획법의 설계공간 탐색의 근사화 성능을 평가하기 위해 반응표면법을 각 실험계획법 별로 생성하여 근사화 정확도 특성을 검토하였다. 또한 최소 중량설계를 위해 최상 설계안의 결과로 부터 실험계획법의 특성에 따른 수치계산 비용, 중량감소 효과 등을 평가하였다. 수동형 갑판 지지 프레임의 구조설계에 대해 Box-Behnken 설계법이 가장 적합한 설계 결과를 나타내었다.

본 연구에서는 철골편심가새골조 시스템을 대상으로 다목적최적화기법을 통해 설계를 수행하고 그 결과를 분석하였다. 최적화 설 계를 위해 유전 알고리즘의 일종인 NSGA-II를 활용하였다. 여기서, 목적함수는 이율배반적 관계를 갖는 구조물량과 층간변위로 하여 최소화되고, 제약조건에는 구조기준에서 요구하는 내력비, 링크의 회전각 등을 포함하였다. 제약조건은 최적화 알고리즘 내에서 각 항목을 위반할수록 목적함수 값을 크게 증가시키는 벌금함수의 형태를 가지고 있다. 설계기준에서 EBF 시스템의 설계규정은 링크 부재만 항복이 허용되며 나머지 부재는 링크 항복 시 발생되는 부재력을 탄성상태에서 견디도록 의도한 역량설계법에 기초한다. 그러나 최적화를 통해 도출된 결과 중 일부는 구조기준의 설계조항은 만족하지만 특정층 링크에 소성변형이 집중되어 연약층을 형성함 으로써 기준에서 의도하는 역량설계의 원칙을 위배하는 결과가 나타났다. 이를 해결하기 위해 모든 링크의 전단 초과강도계수 중 최 대값이 최소값의 1.25배를 넘지 않도록 하는 제약식을 추가하였다. 새로운 제약식을 추가한 경우 모든 최적해는 설계기준과 역량설계의 원칙을 준수하는 것으로 나타났다. 모든 설계안에서 보 경간에 대한 링크의 길이비는 전단링크의 범주에 해당하는 10% ~ 14%였다. 전체적으로 설계안들은 링크의 초과강도 계수비가 가장 지배적인 제약으로 작용하였으며, 구조기준의 요구사항 중 층간변위와 내력비 등의 항목에서 허용치에 비해 매우 보수적으로 설계되었다.

A manufacturing company should produce its products and make a profit to continue its management. With the adoption of a multi-category small-volume production system, manufacturers that produce concrete pump-cine products are carrying out improvement activities to increase their market share amid the business-to-customer business environment. However, the slump in the construction investment environment has led to a decline in sales of concrete pump trucks. The purpose of holding inventory is to prevent loss of sales opportunities with the rate of change in the sales plan, and reducing the rate of change in the product can reduce unnecessary inventory and, in order to realize this, the goal of reducing inventory can be achieved by reviewing the parts that can be designed for common use. Therefore, to reduce the inventory of concrete pump trucks, semi-finished publicization design is necessary. According to the analysis, the frame assembly process of the 32M model is common. Production capacity can be secured without loss of sales opportunity.

본 연구에서 적용한 SMRPF system은 구조물 접합부의 패널존을 고려하는 동시에 지진하중에 대하여 각층별 전단력을 산정하여 댐퍼의 감쇠력과 변위를 결정해준다. 이는 내진설계가 반영되지 않은 구조물에 적용할 경우 부재단면을 변경하지 않고 내진성능을 확보 할 수 있는 감쇠기의 역량 결정이 가능함을 보여 주었다. 또한 본 논문에서 적용한 유전자 알고리즘을 통해 최적설계를 수행한 결과, 무보강 구조물에 비해 점성감쇠기와 패널존을 고려한 SMRPF 강골조 구조물의 총 중량이 약 50%이상 감소되는 것이 확인되었다.

The present study is aimed to calculate the optimal damping according to the seismic load on the structure with a non-seismic design to perform structure analysis considering the deformation of structural joint connection and panel zone; to develop design program equipped with structural stability of the steel frame structures reinforced with the panel zone and viscous dampers, using the results of the analysis, in order to systematically integrate the seismic reinforcement of the non-seismic structures and the analysis and design of steel frame structures. The study results are as follows: When considering the deformation of the panel zone, the deformation has been reduced up to thickness of the panel double plate below twice the flange thickness, which indicates the effect of the double plate thickness on the panel zone, but the deformation showed uniform convergence when the ration is more than twice. The SMRPF system that was applied to this study determines the damping force and displacement by considering the panel zone to the joint connection and calculating the shear each floor for the seismic load at the same time. The result indicates that the competence of the damper is predictable that can secure seismic performance for the structures with non-seismic design without changing the cross-section of the members.

우리나라의 바람은 계절풍, 태풍, 저기압 전선풍으로 나눌 수 있다. 또한 우리나라는 산지가 많고 삼면이 바다로 둘러싸인 지 리적인 특성도 갖고 있다. 이로 인해 각 지역의 풍향마다 풍속이 균일하게 불어오지 않는다. 내풍설계 시 사용하는 풍속은 건축구조기 준에 규정된 100년 재현기대풍속을 전풍향에 대해 동일하게 사용한다. 이 값은 풍향을 고려하지 않기 때문에 다소 보수적인 설계가 될 수 있다. 이 연구에서는 10개 지역을 대상으로 16풍향에 대한 분풍속을 수집하여 풍향별 100년 재현기대풍속을 산출하였다. 기상청에 서 수집한 자료를 균질하게 하기 위해 풍향별로 유효높이를 고려하였고, 지표면조도구분을 하는 방법으로 가스트계수방법과 목측방법을 사용하였다. 풍향별 100년 재현기대풍속을 산정하기 위한 확률분포는 Gumbel분포를 사용하였고, 경험적 초과확률로는 Hazen방법 을 이용하였으며, Gumbel분포와 Hazen방법의 적합성은 적합성평가함수에 의해 판단하였다. 이것을 토대로 각 지역의 풍향계수를 산출하였고, 풍향계수의 비교를 통해 지역별, 풍향별 풍속의 특성을 파악하였다.

The hydro-forming design process of the sub-frame side members was studied using a high strength steel of 440 MPa in tensile strength. In the part design stage of the side member, the cross section analysis and the overall process design of the part shape were done. In the detailed simulation results, the maximum thickness reduction rate due to hydro-forming was predicted to be 13% and this was predicted to be a safe level without cracking. The end curvature was reduced to increase the stiffness of the part to design more secure parts and two types of grooves were added to the cross section and compared. The thickness reduction rates of the narrow and wide were improved by 18.6% and 15.6%, respectively when the narrow and wide grooves were added.

Now that problems with force-based seismic design have been clearly identified, design is inclined toward displacement-based methods. One such widely used method is Direct-Displacement-Based Design (DDBD). Yet, one of the shortcomings of DDBD is considering higher-mode amplification of story shear, moments, and displacements using equations obtained from limited parametric studies of regular planar frames. In this paper, a different approach to account for higher-mode effects is proposed. This approach determines the lateral secant stiffness of the building frames that fulfill the allowable inter-story drift without exceeding the desired story displacements. Using the stiffness, an elastic response spectrum analysis is carried out to determine elastic higher-mode force effects. These force effects are then combined with DDBD-obtained first-mode force effects using the appropriate modal superposition method so that design can be performed. The proposed design procedure is verified using Nonlinear Time History Analysis (NTHA) of twelve planar frames in four categories accounting for mass and stiffness irregularity along the height. In general, the NTHA response outputs compared well with the allowable limits of the performance objective. Thus, it fulfills the aim of minimizing the use of NTHA for planar frame buildings, thereby saving computational resources and effort.

Recently, the use of tubes in the manufacturing of the automobile parts has increased and therefore many automotive manufactures have tried to use hydro-forming technology. The hydro-forming technology may cause many advantages to automotive applications in terms of better structural integrity of the parts, lower cost from fewer part count, material saving, weight reduction, lower spring-back, improved strength and durability and design flexibility. In this study, the whole process of sub-frame parts development by tube hydro-forming using steel material is presented. At the part design stage, it requires feasibility study and process design aided by CAE (computer aided design) to confirm hydro-formability in details. Overall possibility of hydro-formable sub-frame parts could be examined by cross sectional analyses. All the components of prototyping tools are designed and interference with press is examined from the point of geometry and thinning.

This paper is concerned with the optimal design of recliner chair frame. It is necessary for recliner chair frame that is endurable for the repeated load of human sitting. And this paper studies the selected recliner chair frame that is produced in the regional company. The company has not designed and made this chair by the mechanical engineering review. So the current frame structure and parts in this chair frame are studied and researched to develop the new frame structure with mechanical engineering design concepts. This research reported the investigation of new design of recliner chair frame by stress analysis and the verification of mechanical safety. This result will be adopted to design specification of new recliner chair frame

This paper deals with steel braced frame as increasing the lateral strength and ductility in order to seismic retrofit of existing buildings and discusses the designing criteria and calculation method of retrofitted buildings. The addition of steel braced frame can be effective for increasing the lateral strength and ductility of existing buildings. However, There is a problem in utilizing this method. It is the approach to provide an adequate connection between the existing RC frame and the installed steel braced frame, because global strength by failure mode(three type) depends on detail of connection and strength of existing RC frame. So, the designer must be confirmed if it satisfies the required performance or not. Failure mode of type I is the most appropriate for increasing the lateral strength and ductility. Seismic performance evaluation and strength calculation of seismic retrofit are performed by guideline by KISTEC(Korea Infrastructure Safety & Technology)’s “seismic performance evaluation and rehabilitation of existing buildings” and Japan Building Disaster Prevention Association. Buildings are modeled and non-linear pushover analysis are performed using MIDAS program.

This study is concerned about the optimal design of the main frame in a moper. Mopper is widely used for cleaning in the fields such as airport, subway, train station, large shopping mall, department store, hospital, government buildings, school, industrial building floor, etc. Especially, main frame in mopper are stressed by high, mostly loads. Nevertheless, design of main frame is dependent on experience, and it will cause reliability reduction and cost increase. This research purpose is to propose and verify a method to achieve higher product quality, lower costs, and far less physical testing. In this study, design parameters used for optimization are each thickness of 4 square pipes and 1 plate in the main frame. The result after optimization showed that the weight of main frame reduced to maximum 6.5% when compared with the initial design in main frame.

The object of this study is concerned about the optimal design of the supporting frame in a twist screen. Twist screen is widely used for grading and screening materials in the fields such as coal-selecting, mining-selecting, building materials, electrical power and chemical industry, etc. It is composed of base, supporting frame, vibrator, screen, spring, trough, clamp and etc. Especially, supporting frame in twist screen are stressed by high load, mostly it is shock-type loads. Nevertheless, design of base is dependent on experience, and it will cause reliability reduction and cost increase. The supporting plate is composed by the upper plate, the bracket and etc. This research purpose is to propose and verify a method to achieve higher product quality, lower costs, and far less physical testing. In this study, design parameters used for optimization are the upper plate thickness(8㎜, 10㎜, 12㎜) and the bracket thickness(8㎜, 10㎜, 12㎜) in the supporting frame. The result showed that base weight reduced to maximum 25.8% when compared with the current twist screen.

The interest for the stability of the structures against earthquake, which is increasing recently, is rapidly increasing. But, currently, school buildings among the reinforced concrete(RC) structures in Korea are not designed with seismic design or there are many cases of being designed with the old seismic design code, so it is estimated to have not only lives but also a great deal of economic damage are likely to occur when an earthquake occurs. In this study, proposed horizontal friction system(HFS) with rotary friction damper installed as a method to reinforce strength and hardness and to increase ductility for the low story structure of 5 stories or lower such as school buildings. For the seismic retrofitting design with horizontal friction system in which rotary friction damper is installed, Peak displacement response ratio according to elastic and inelastic behavior and ductility demand is calculated to decide elastic stiffness and strength of the HFS, design model and procedure to decide the capacity of HFS thereof is decided, and the feasibility and performance are reviewed through pushover analysis.

목 적: 본 연구에서는 CA(Cellulose Acetate; CA)안경테 전용 가공장비의 40,000 rpm급 고속 주축시스템에 대하여 구조설계 단계에서 안정성을 검토하였다. 방 법: 안경테 전용 주축시스템의 베어링 윤활과 예압구조 선정 및 주축계의 정/동/열적 특성 분석을 통하여 고유진동수, 최대변형, 열변위를 예측하였다. 결 과: 안경테 가공장비 주축의 윤활시스템은 최소미량급유방식인 오일-에어 방식을 채택하였으며 정동적분석 결과 안정성이 확보되었으나, 열변위량은 최대 0.135 mm로 고속 회전 시 주축 발란싱과 성능에 문제가 발생 할 것으로 예측되었다. 결 론: CA안경테 전용 가공장비의 40,000 rpm급 고속 주축시스템을 설계 단계에서부터 윤활 및 예압구조를 선정하였으며, 정동적분석을 통하여 구조안정성이 우수함을 예측하였다. 그러나 회전에 따른 열상승 및 열적변형에 취약하여 이에 대한 대책이 필요할 것으로 나타났다.