Yoojeong Noh

Optimization of Door Hinges of a Large Refrigerator

Key Words: Design Optimization(최적설계), Hinge Mechanism(힌지 메커니즘), PQRSM(순차적 2차 반응표면법), PIDO(통합절차 최적설계)초록: 대형냉장고의 도어 힌지는 냉장고 도어의 개폐 동작을 원활하게 하고, 도어의 하중과 도어개폐로 인한 충격을 견디는 구조 안전성이 요구된다. 하지만, 도어 힌지는 복잡한 힌지 메커니즘과 민감한 구조 안전성으로 인해 설계 시 어려움이 많다. 본 논문에서는 스프링 응답 특성, 공간제약, 구조강도 성능을 만족하는 메커니즘을 설계하고, 메커니즘을 둘러싼 외부 프레임의 부피를 최소화하여 힌지의 생산 단가를 절감하고자 한다. 이를 위해 PIDO(progress integration and design optimization) 기술을 이용하여 모든 설계절차를 자동화함으로써 설계의 효율성을 높이는 성과를 거두었으며, 최적화 결과 목표로 하는 힌지 메커니즘 성능과 구조안정성을 개선하면서 힌지 프레임 질량의 24%를 절감하였다.Abstract: Door hinges of large refrigerators are required to ensure that the doors open and close smoothly in addition to supporting door weights and enduring the impact loads due to door opening and closing. However, door hinge design is difficult because of complex hinge mechanisms and sensitive structural safety. In this study, the mechanism satisfying the required spring response, space constraints, and structural strength is optimized, and the volume of the outer frame covering the hinge mechanism is minimized for reducing production costs. The entire design process is automated using the PIDO(Progress Integration and Design Optimization) technique, which achieves an efficient design process. Therefore, the frame mass is reduced to 24%, and the mechanism performance and structural stability are improved.

A Comparison Study on Statistical Modeling Methods

Abstract The statistical modeling of input random variables is necessary in reliability analysis, reliability-based design optimization, and statistical validation and calibration of analysis models of mechanical systems. In statistical modeling methods, there are the Akaike Information Criterion (AIC), AIC correction (AICc), Bayesian InformationCriterion, Maximum Likelihood Estimation (MLE), and Bayesian method. Those methods basically select the best fitted distribution among candidate models by calculating their likelihood function values from a given data set. Thenumber of data or parameters in some methods are considered to identify the distribution types. On the other hand,the engineers in a real field have difficulties in selecting the statistical modeling method to obtain a statistical modelof the experimental data because of a lack of knowledge of those methods. In this study, commonly used statisticalmodeling methods were compared using statistical simulation tests. Their advantages and disadvantages were then analyzed. In the simulation tests, various types of distribution were assumed as populations and the samples were generated randomly from them with different sample sizes. Real engineering data were used to verify each statisticalmodeling method.

Optimization of Base Plates and Contact Switches in Trunk Latches

Automobile trunk latches enable trunks to be opened and closed by a latch mechanism, which can be selectively positioned between a locked condition and an open condition. To maintain structural and electronic performance of the trunk latch, the latch needs to endure impact load that occurs in its open and close motion, and a dynamic mechanism needs to be electronically controled by a contact switch connected with a small DC motor. A base plate, which is the most important component relating to the structural safety, commonly uses a high stiffness material SAPH440-P with high manufacturing cost. In this paper, through structural analysis and optimization, production cost is significantly reduced by replacing SAPH440-P used in some region of the base plate with engineering plastic PBT GF 20%. The optimized contact switch reduces difference between distributed pressures of its two legs, which leads to improve the electronic performance of the trunk latch.