한국형 포장설계법(KPRP)은 한국의 기후, 교통, 재료 조건을 반영하여 개발된 포장설계법으로, 성능 기반 분석과 역학적-경험적 원 리를 결합하여 국내 도로포장의 내구성과 효율성 향상에 기여해왔다. KPRP는 지역별 환경 데이터, 교통 하중, 재료 특성을 고려하 여 최적의 포장 구조를 설계하며, 2011년 개발 이후 도로포장의 수명 연장과 경제성 향상을 이루어냈다. 그러나 KPRP에 적용되는 기후 및 교통 데이터는 2000년대 초반의 자료를 기반으로 하고 있어, 현재 기준으로 약 10년 이상의 차이가 존재한다. 이에 따라 최 신 데이터를 반영하여 포장설계를 개선할 필요성이 제기되고 있다. 본 연구에서는 최근 10년간의 최신 기후 데이터를 활용하여 줄눈 콘크리트 포장(JCP)의 콘크리트 슬래브 컬링 시간을 계산하고, 이를 기반으로 온도응력 및 교통응력의 산정 방식을 현 시점에 맞게 개선하고자 한다. 또한, 2023년 도로포장관리시스템(PMS) 데이 터를 이용하여 한국도로공사가 관리하는 모든 고속국도 중 JCP가 적용된 구간을 대상으로 표면 균열(SD), 설계 차로별 AADT, 관 리구간별 도로 연장, 차로 폭 등의 데이터를 분석하였다. 이를 통해 각 도로의 피로균열율을 산정하고, 고속국도를 대상으로 줄눈 콘 크리트 포장의 전이함수를 개선하여 보다 정밀한 설계를 가능하게 하고자 한다. 본 연구는 최신 기후 및 교통 데이터를 반영한 KPRP 기반 줄눈 콘크리트 포장설계의 실현에 기여할 것으로 기대된다.

In order support the design support system of small and medium-sized shipbuilding companies that carry out designs using 2D CAD, this study developed a system that automatically calculates the cable length by extracting the Y-axis value expressed as text data in 2D CAD. By setting the equipment where the cable starts and ends, the essential route and the installation rate were checked so that the optimal route of the cable could be calculated. As a result, the value calculated based on the optimal route and length of the cable by extracting the data of 2D CAD through this study was the same as the value previously calculated by the actual user, and the installation rate was less than 130% so there was no problem with the on-site installation. In addition, it was confirmed that the cable length calculated through this was reduced by about 7% compared to the existing work.

Multidisciplinary Design Optimization(MDO) method that considers principles in various fields affecting big scale structure and system design at the same time is used. Because most variables are connected many engineering phenomena under the classic optimized design method(all-in-one design approach), it is hard to judge the meaning of final design solution obtained, and there are cases where all variables converge before reaching the optimal design value in large-scale design problems with many variables. Collaborative Optimization (CO) method, the most advanced MDO approach, is used to efficiently solve these optimum problems, to efficiently analyze design problems involving numerous design variables and constraints and in which various engineering phenomena occur. However, the application of the MDO problem to CO introduces a number of numerical problems by destroying the numerical properties of the original optimal design problem. Therefore, this study researches one solution by listing the problems of CO after organizing various approaches of MDO.

Liquid hydrogen, a promising energy carrier, necessitates robust storage and transportation systems due to its extremely low boiling point. Consequently, the development of reliable cryogenic adhesives and standardized testing protocols is crucial. This study focused on optimizing the design of a gripper used in single lap shear tests for evaluating cryogenic adhesives, specifically targeting the challenges posed by low-temperature conditions that induce slippage at the gripper interface. The optimal design was performed using a total of five variables, including the position and size of the gripper. By employing the genetic algorithm coupled with finite element analysis, we exhaustively searched through over 1000 models to identify the optimal gripper geometry. We successfully minimized stress concentration at the gripper region while maintaining a uniform stress distribution on the non-bonded surface. Furthermore, the study explored the impact of symmetric versus asymmetric gripper configurations on test results. The findings revealed that symmetric grippers generally yielded more consistent and reliable data. This study's results enable the accurate and stable execution of lap shear tests under the temperature conditions of liquefied hydrogen.

공항은 다른 어떤 기반시설보다 복잡하고 사고시 매우 치명적이기 때문에 공항 계획/설계시 운영적인 측면을 고려한 면밀한 검토가 필요하다. 공항 건설이후 실제 항공기가 어떻게 운영되는지 시뮬레이션하고 문제점을 사전에 예측함으로써 항공기 운항 안전성을 확보할 수 있기 때문이다. 최근 도로/공항의 경우 디지털 트윈 기반의 시뮬레이션 프로그램으로 설계, 분석하는 사례가 많다. 이러한 기조에 맞춰 공항에서도 시뮬레이션 프로그램인 AviPLAN을 활용하여 에어사이드 배치 설계를 수행하고 있으며, 인천국제공항공사와 한국공항공사에서도 활용하고 있다. 본 연구에서는 기존 국내외 공항에 AviPLAN 프로그램을 활용하여 최적화 설계를 수행하였고 산출된 포장물량 절감사례를 바탕으로 에어사이드 시설 배치가 얼마나 중요한지 확인하고자 하였다.

본 논문에서는 다이나믹크리깅 대리모델 기반 자동차 브레이크 패드 마모량 측정센서 브라켓의 설계최적화를 소개한다. 브레이크 작동시 마찰재 바닥의 온도가 600°C 이상으로 상승하고, 이 열이 전달되어 센서의 기능을 상실시킨다. 따라서 열전달을 최소화하는 브라켓 형상의 설계최적화는 필수적이다. 최적화에 소요되는 계산비용을 절감하기 위해 다이나믹크리깅 대리모델로 열전달 시뮬레 이션을 대체하였다. 다이나믹크리깅은 최적의 상관함수와 기저함수를 선정하였으며, 정확한 대리모델을 도출하였다. 최적화 결과 센 서위치의 온도가 초기모델에 비해 7.57% 감소하였으며, 이를 열전달 시뮬레이션으로 다시 한번 확인하여 대리모델 기반 최적설계가 유의미함을 검증하였다.

Taguchi method is one of the most popular approaches for design optimization such that performance characteristics become robust to uncontrollable noise variables. However, most previous Taguchi method applications have addressed a single-characteristic problem. Problems with multiple characteristics are more common in practice. The multi-criteria decision making(MCDM) problem is to select the optimal one among multiple alternatives by integrating a number of criteria that may conflict with each other. Representative MCDM methods include TOPSIS(Technique for Order of Preference by Similarity to Ideal Solution), GRA(Grey Relational Analysis), PCA(Principal Component Analysis), fuzzy logic system, and so on. Therefore, numerous approaches have been conducted to deal with the multi-characteristic design problem by combining original Taguchi method and MCDM methods. In the MCDM problem, multiple criteria generally have different measurement units, which means that there may be a large difference in the physical value of the criteria and ultimately makes it difficult to integrate the measurements for the criteria. Therefore, the normalization technique is usually utilized to convert different units of criteria into one identical unit. There are four normalization techniques commonly used in MCDM problems, including vector normalization, linear scale transformation( max-min, max, or sum). However, the normalization techniques have several shortcomings and do not adequately incorporate the practical matters. For example, if certain alternative has maximum value of data for certain criterion, this alternative is considered as the solution in original process. However, if the maximum value of data does not satisfy the required degree of fulfillment of designer or customer, the alternative may not be considered as the solution. To solve this problem, this paper employs the desirability function that has been proposed in our previous research. The desirability function uses upper limit and lower limit in normalization process. The threshold points for establishing upper or lower limits let us know what degree of fulfillment of designer or customer is. This paper proposes a new design optimization technique for multi-characteristic design problem by integrating the Taguchi method and our desirability functions. Finally, the proposed technique is able to obtain the optimal solution that is robust to multi-characteristic performances.

In the automobile manufacturing industry, lightweight design is one of the essential challenges to be solved fundamentally. The vehicle wheels are classified as safety related components as the main substructure of the vehicle. In this study, we illustrate a technique for selecting the appropriate number of spokes. Based on the basic model of the selected number of spokes, we propose a method to maintain stiffness and design lightweight using topology optimization software. Based on the basic model of the selected number of spokes, it was redesigned to be lightweight while maintaining stiffness by utilizing topology optimization software. By comparing and reviewing the structural analysis results of the basic model and the redesigned model, a design technique that can maintain structural safety and reduce wheel mass was proposed.

본 논문에서는 AI 기반 설계 탐색 기법을 활용하여 선박의 주요 치수 최적화를 수행하였다. 설계 탐색 기법은 최적화 프로그램 HEEDS의 SHERPA 알고리즘을 사용하였다. 유동 해석은 상용 CFD 코드인 STAR-CCM+를 사용하였고, 주요 치수 변환은 전처리 과정에서 JAVA Script와 Python을 사용하여 선박의 치수가 자동으로 변환되도록 설정하였다. 대상 선박은 소형 쌍동선형으로 주요 치수 최적화는 한쪽 선형의 길이, 폭, 흘수 그리고 단동선형 간의 간격에 대하여 수행되었다. 최적화 알고리즘에 사용된 목적함수는 총저항이며, 내부 의 장 시스템의 크기 등을 고려한 배수 체적의 범위를 제한조건으로 선정하였다. 그 결과 최적 선형의 주요 치수는 기존 선형 대비 ±5% 내 에서 변화가 있었고 총저항은 약 11% 개선된 결과를 보였다. 본 연구를 통해 선박의 형상을 직접 변경하지 않더라도 주요 치수 최적화를 통해 선박의 저항 성능이 향상됨을 확인하였고, 다양한 선박의 주요 치수 최적화를 통한 성능 향상에 활용이 될 것으로 기대한다.

Companies are making design changes by improving product quality and function to succeed while meeting customer requirements continuously. Design changes are changing the product BOM's amount, item, specification, and shape while causing a change in the product's structure. At this time, the problem of inventory exhaustion of parts before design change is a big topic. If the inventory exhaustion fails, the pieces before the design change become unused and are discarded, resulting in a decrease in asset value, and the quality cost of the design change affects the company's profits. Therefore, it is necessary to decide to minimize quality costs while minimizing waste inventory costs at the time of application of design changes. According to the analysis, priorities should be prioritized according to urgency because the quantity of items before the design change affects the applied lead time.

현대 사회가 복잡해지고 기술이 진보하면서 하나의 제품을 설계할 때 단일 특성이 아닌 다 특성을 갖는 제품을 설계하는 것이 요구되고 있다. 다 특성 설계 최적화 문제에서는 설계 변수의 최적값이 특성별로 다르게 되는 현상이 발생하고 이에 따라 하나의 특성에 대한 결과값이 좋아지면 다른 특성에 대한 결과값이 나빠지는 경우에 대해서 trade-off가 필요하다. 따라서 다 특성을 갖는 제품 설계 시 각각의 특성에 대한 성능을 최대화할 수 있는 효율적인 설계 방법의 필요성이 중요한 문제로 떠오르고 있다. 다 특성을 갖는 제품을 설계하는 연구는 오래전부터 중요한 문제로 인식되어 왔는데, 단일 특성에 대해 성능을 최대화하며 강건한 설계를 할 수 있는 다구치 기법과 다기준/다특성 의사 결정 방법인 TOPSIS(Technique for Order of Preference by Similarity to Ideal Solution), GRA(Grey relational analysis), PCA(Principle Component Analysis), Fuzzy Logic System을 통합한 연구들이 진행되어 왔다. 하지만 기존 연구들은 각각의 설계 대안들에 대해 다 특성 결과값에 대한 점수를 통합하여 종합 점수를 비교해 최적의 설계안을 도출할 뿐 설계자의 호감도에 대한 정보는 설계에 반영하지 못한다. 따라서 본 연구에서는 다구치 기법을 기반으로 각각의 특성들에 대한 설계자의 서로 다른 호감도를 함수로써 표현하여 강건성과 함께 설계자의 호감도를 동시에 설계에 반영할 수 있는 방법을 제안한다.

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.

In this paper, a method of reducing the weight of vehicle wheels through topology optimization by finite element method is proposed. Recently, various environmental pollution caused by the operation of vehicles is gradually increasing, and this has a great correlation with the fuel efficiency of the vehicle. Therefore, it is required to reduce the weight of the vehicle to increase fuel efficiency. Among them, the vehicle's wheels are a key part of vehicle acceleration and braking, and passenger safety. Because the shape of the wheels is different, various effects such as reduced fuel economy and reduced airpower occur as well as aesthetic factors. The stiffness of the wheels plays an important role in transmitting the vehicle's power to the tires and braking. In this study, to reduce weight while satisfying the stiffness value, we propose to use topology optimization to design an arbitrary shape according to the number of spokes on the wheel.